Assembly and catalytic activity of short prion-inspired peptides.

Enzymes play a crucial role in biochemical reactions, but their inherent structural instability limits their performance in industrial processes. In contrast, amyloid structures, known for their exceptional stability, are emerging as promising candidates for synthetic catalysis. This article explores the development of metal-decorated nanozymes formed by short peptides, inspired by prion-like domains. We detail the rational design of synthetic short Tyrosine-rich peptide sequences, focusing on their self-assembly into stable amyloid structures and their metallization with biologically relevant divalent metal cations, such as Cu2+, Ni2+, Co2+ and Zn2+. The provided experimental framework offers a step-by-step guide for researchers interested in exploring the catalytic potential of metal-decorated peptides. By bridging the gap between amyloid structures and catalytic function, these hybrid molecules open new avenues for developing novel metalloenzymes with potential applications in diverse chemical reactions.

Plant Protease Inhibitors as Emerging Antimicrobial Peptide Agents: A Comprehensive Review.

Antimicrobial peptides (AMPs) are important mediator molecules of the innate defense mechanisms in a wide range of living organisms, including bacteria, mammals, and plants. Among them, peptide protease inhibitors (PPIs) from plants play a central role in their defense mechanisms by directly attacking pathogens or by modulating the plant's defense response. The growing prevalence of microbial resistance to currently available antibiotics has intensified the interest concerning these molecules as novel antimicrobial agents. In this scenario, PPIs isolated from a variety of plants have shown potential in inhibiting the growth of pathogenic bacteria, protozoans, and fungal strains, either by interfering with essential biochemical or physiological processes or by altering the permeability of biological membranes of invading organisms. Moreover, these molecules are active inhibitors of a range of proteases, including aspartic, serine, and cysteine types, with some showing particular efficacy as trypsin and chymotrypsin inhibitors. In this review, we provide a comprehensive analysis of the potential of plant-derived PPIs as novel antimicrobial molecules, highlighting their broad-spectrum antimicrobial efficacy, specificity, and minimal toxicity. These natural compounds exhibit diverse mechanisms of action and often multifunctionality, positioning them as promising molecular scaffolds for developing new therapeutic antibacterial agents.

Cryo-EM structures of functional and pathological amyloid ribonucleoprotein assemblies.

Amyloids are implicated in neurodegenerative and systemic diseases, yet they serve important functional roles in numerous organisms. Heterogeneous nuclear ribonucleoproteins (hnRNPs) represent a large family of RNA-binding proteins (RBPs) that control central events of RNA biogenesis in normal and diseased cellular conditions. Many of these proteins contain prion-like sequences of low complexity, which not only assemble into functional fibrils in response to cellular cues but can also lead to disease when missense mutations arise in their sequences. Recent advances in cryo-electron microscopy (cryo-EM) have provided unprecedented high-resolution structural insights into diverse amyloid assemblies formed by hnRNPs and structurally related RBPs, including TAR DNA-binding protein 43 (TDP-43), Fused in Sarcoma (FUS), Orb2, hnRNPA1, hnRNPA2, and hnRNPDL-2. This review provides a comprehensive overview of these structures and explores their functional and pathological implications.

Decoding the role of coiled-coil motifs in human prion-like proteins.

Prions are self-propagating proteins that cause fatal neurodegenerative diseases in humans. However, increasing evidence suggests that eukaryotic cells exploit prion conformational conversion for functional purposes. A recent study delineated a group of twenty prion-like proteins in humans, characterized by the presence of low-complexity glutamine-rich sequences with overlapping coiled-coil (CCs) motifs. This is the case of Mediator complex subunit 15 (MED15), which is overexpressed in a wide range of human cancers. Biophysical studies demonstrated that the prion-like domain (PrLD) of MED15 forms homodimers in solution, sustained by CCs interactions. Furthermore, the same coiled-coil (CC) region plays a crucial role in the PrLD structural transition to a transmissible ß-sheet amyloid state. In this review, we discuss the role of CCs motifs and their contribution to amyloid transitions in human prion-like domains (PrLDs), while providing a comprehensive overview of six predicted human prion-like proteins involved in transcription, gene expression, or DNA damage response and associated with human disease, whose PrLDs contain or overlap with CCs sequences. Finally, we try to rationalize how these molecular signatures might relate to both their function and involvement in disease.

Purification and Characterization of a Novel Thermostable Papain Inhibitor from Moringa oleifera with Antimicrobial and Anticoagulant Properties.

Plant cystatins (or phytocystatins) comprise a large superfamily of natural bioactive small proteins that typically act as protein inhibitors of papain-like cysteine proteases. In this report, we present the purification and characterization of the first phytocystatin isolated from Moringa oleifera (MoPI). MoPI has a molecular mass of 19 kDa and showed an extraordinary physicochemical stability against acidic pHs and high temperatures. Our findings also revealed that MoPI is one of the most potent cysteine protease inhibitors reported to date, with Ki and IC50 values of 2.1 nM and 5.7 nM, respectively. More interestingly, MoPI presents a strong antimicrobial activity against human pathogens such as Enterococcus faecalis and Staphylococcus aureus. In addition, MoPI also showed important anticoagulant activity, which is an unprecedented property for this family of protease inhibitors. These results highlight the pharmaceutical potential of this plant and its derived bioactive molecules.

Substrate Specificity and Structural Modeling of Human Carboxypeptidase Z: A Unique Protease with a Frizzled-Like Domain.

Metallocarboxypeptidase Z (CPZ) is a secreted enzyme that is distinguished from all other members of the M14 metallocarboxypeptidase family by the presence of an N-terminal cysteine-rich Frizzled-like (Fz) domain that binds Wnt proteins. Here, we present a comprehensive analysis of the enzymatic properties and substrate specificity of human CPZ. To investigate the enzymatic properties, we employed dansylated peptide substrates. For substrate specificity profiling, we generated two different large peptide libraries and employed isotopic labeling and quantitative mass spectrometry to study the substrate preference of this enzyme. Our findings revealed that CPZ has a strict requirement for substrates with C-terminal Arg or Lys at the P1' position. For the P1 position, CPZ was found to display specificity towards substrates with basic, small hydrophobic, or polar uncharged side chains. Deletion of the Fz domain did not affect CPZ activity as a carboxypeptidase. Finally, we modeled the structure of the Fz and catalytic domains of CPZ. Taken together, these studies provide the molecular elucidation of substrate recognition and specificity of the CPZ catalytic domain, as well as important insights into how the Fz domain binds Wnt proteins to modulate their functions.

Phenotype and resistance patterns of 10 resistant prolactinomas.

BACKGROUND: Dopamine agonists (DA) are the first-line therapy in prolactinomas, but they fail to decrease prolactin (PRL) levels and/or tumor size in some of these tumors, which are labeled as resistant prolactinomas (RP). To date, risk factors for DA resistance are not fully understood and management of DA-RP is not well established. METHODS: We retrospectively recorded clinical, biochemical and radiological features, as well as management and outcome, of all cabergoline (CAB)-RP attended at the Endocrinology department of a tertiary hospital between 1995 and 2016. CAB resistance was defined as the failure to normalize PRL (biochemical resistance, BR) or reduce tumor size by at least 50% (morphological resistance, MR) with a CAB dose up to 2mg/week (or 3mg/week in cases where lower doses were not tested) for at least 3 months. RESULTS: Ten CAB-RP were found. The mean age of the cohort was 30.6 years and 50% of subjects were male. The average tumor size was 1.78cm (80% macroadenomas). The mean maximal dose of CAB was 3.8mg/week. Five patients showed isolated MR, four combined MR+BR and only one isolated BR. MR patients were more often males and older than MR+BR patients. Transsphenoidal surgery achieved normalization of PRL and/or disappearance of tumor in three of seven patients. At the end of follow up all patients had controlled PRL levels (with or without CAB) and most of them bore a visible although stable tumor. CONCLUSIONS: Isolated MR and combined MR+BR are the most frequent patterns of DA resistance whereas isolated BR seems to be uncommon. Our data support a high tumor size but not male gender as a risk factor for DA resistance.

Curvature induction and membrane remodeling by FAM134B reticulon homology domain assist selective ER-phagy.

FAM134B/RETREG1 is a selective ER-phagy receptor that regulates the size and shape of the endoplasmic reticulum. The structure of its reticulon-homology domain (RHD), an element shared with other ER-shaping proteins, and the mechanism of membrane shaping remain poorly understood. Using molecular modeling and molecular dynamics (MD) simulations, we assemble a structural model for the RHD of FAM134B. Through MD simulations of FAM134B in flat and curved membranes, we relate the dynamic RHD structure with its two wedge-shaped transmembrane helical hairpins and two amphipathic helices to FAM134B functions in membrane-curvature induction and curvature-mediated protein sorting. FAM134B clustering, as expected to occur in autophagic puncta, amplifies the membrane-shaping effects. Electron microscopy of in vitro liposome remodeling experiments support the membrane remodeling functions of the different RHD structural elements. Disruption of the RHD structure affects selective autophagy flux and leads to disease states.

ACROSTART: A retrospective study of the time to achieve hormonal control with lanreotide Autogel treatment in Spanish patients with acromegaly.

OBJECTIVES: The ACROSTART study was intended to determine the time to achieve normalization of GH and IGF-I levels in responding patients with acromegaly administered different dosage regimens of lanreotide Autogel (Somatuline® Autogel®). METHODS: From March 2013 to October 2013, clinical data from 57 patients from 17 Spanish hospitals with active acromegaly treated with lanreotide for ≥4 months who achieved hormonal control (GH levels <2.5ng/ml and/or normalized IGF-I levels in ≥2 measurements) were analyzed. The primary objective was to determine the time from start of lanreotide treatment to hormonal normalization. RESULTS: Median patient age was 64 years, 21 patients were male, 39 patients had undergone surgery, and 14 patients had received radiotherapy. Median hormonal values at start of lanreotide treatment were: GH, 2.6ng/ml; IGF-I, 1.6×ULN. The most common starting dose of lanreotide was 120mg (29 patients). The main initial regimens were 60mg/4 weeks (n=13), 90mg/4 weeks (n=6), 120mg/4 weeks (n=13), 120mg/6 weeks (n=6), and 120mg/8 weeks (n=9). An initial treatment regimen with a long interval (≥6 weeks) was administered in 25 patients. Mean duration of lanreotide treatment was 68 months (7-205). Median time to achieve hormonal control was 4.9 months. Injections were managed without healthcare assistance in 13 patients. Median number of visits to endocrinologists until hormonal control was achieved was 3. Fifty-one patients were "satisfied"/"very satisfied" with treatment and 49 patients did not miss any dose. CONCLUSIONS: Real-life treatment with lanreotide Autogel resulted in early hormonal control in responding patients, with high treatment adherence and satisfaction despite disparity in starting doses and dosing intervals.

Adding value to the chia (Salvia hispanica L.) expeller: Production of bioactive peptides with antioxidant properties by enzymatic hydrolysis with Papain.

Chia expeller is a by-product of the extrusion process of chia seeds generated during oil production. Typically, this material is non-utilized or used for non-valuable applications. In the present work, the chia expeller was hydrolysed with Papain and the antioxidant properties of the resultant peptides were evaluated. Papain treatment of the chia seed expeller demonstrated an enrichment of low molecular weight peptides (molecular weight <15 kDa) as determined by SDS-PAGE and MALDI-TOF/MS analyses. Such peptides showed a potent radical scavenging effect in vitro against 1,1-diphenyl-2-picrylhydrazyl (DPPH) and 2,2'-Azino-bis (3-ethylbenzothiazoline-6-sulfonic acid) diammonium salt (ABTS) radicals in comparison with those non-hydrolysed samples. Taken together our results demonstrate the generation of functional peptides from the chia expeller by enzymatic hydrolysis with Papain. This value-added hydrolysate can be potentially included as a supplement in functional food and nutraceutical products.

Versatile iron-catechol-based nanoscale coordination polymers with antiretroviral ligand functionalization and their use as efficient carriers in HIV/AIDS therapy.

A novel chemical approach integrating the benefits of nanoparticles with versatility of coordination chemistry is reported herein to increase the effectiveness of well-known HIV antiretroviral drugs. The novelty of our approach is illustrated using a catechol ligand tethered to the known antiretroviral azidothymidine (AZT) as a constitutive building block of the nanoparticles. The resulting nanoscale coordination polymers (NCPs) ensure good encapsulation yields and equivalent antiretroviral activity while significantly diminishing its cytotoxicity. Moreover, this novel family of nanoparticles also offers (i) long-lasting drug release that is dissimilar inside and outside the cells depending on pH, (ii) triggered release in the presence of esterases, activating the antiviral activity in an on-off manner due to a proper chemical design of the ligand and (iii) improved colloidal stabilities and cellular uptakes (up to 50-fold increase). The presence of iron nodes also adds multifunctionality as possible contrast agents. The present study demonstrates the suitability of NCPs bearing pharmacologically active ligands as an alternative to conventional antiretroviral treatments.

Ectopic Cushing syndrome: Report of 9 cases. / Síndrome de Cushing ectópico: descripción de 9 casos.

INTRODUCTION: Ectopic Cushing's syndrome (ECS) is a rare condition caused by ACTH secretion by extrapituitary tumors. Its low frequency makes it difficult to acquire experience in its management. The aim of this study was to describe patients with ECS seen at the endocrinology department of a tertiary hospital over 15 years. METHODS: This was a retrospective study of the clinical, biochemical and radiographic data, treatment, and course of patients with ECS seen from 2000 to 2015. RESULTS: Nine patients (6 of them female) with a mean age of 47 years were included in the study. The clinical syndrome developed in less than 3 months in all cases but one, and most patients also had edema, hyperpigmentation and/or hypokalemia. Mean urinary free cortisol and ACTH levels were 2,840µg/24h and 204pg/mL respectively. The ectopic origin was confirmed by a combination of dynamic non-invasive tests and radiographic studies in most cases. The tumor responsible could be identified in 8 cases, and 7 patients had metastatic dissemination. Primary treatment was surgery in one patient, surgery combined with systemic therapy in 3, and chemotherapy in the other 3 patients. Bilateral adrenalectomy was required in 4 patients to control hypercortisolism. After a mean follow-up of 40 months, 3 patients died, 5 were still alive, and one had been lost to follow-up. CONCLUSIONS: Our study confirms that ECS covers a wide spectrum of tumors of different aggressiveness and nature. The ectopic origin of Cushing's syndrome can usually, be suspected and confirmed in most cases without the need for invasive tests. Control of both hypercortisolism and the tumor requires multiple treatment modalities, and multidisciplinary management is recommended.

Biochemical and MALDI-TOF Mass Spectrometric Characterization of a Novel Native and Recombinant Cystine Knot Miniprotein from Solanum tuberosum subsp. andigenum cv. Churqueña.

Cystine-knot miniproteins (CKMPs) are an intriguing group of cysteine-rich molecules that combine the characteristics of proteins and peptides. Typically, CKMPs are fewer than 50 residues in length and share a characteristic knotted scaffold characterized by the presence of three intramolecular disulfide bonds that form the singular knotted structure. The knot scaffold confers on these proteins remarkable chemical, thermal, and proteolytic stability. Recently, CKMPs have emerged as a novel class of natural molecules with interesting pharmacological properties. In the present work, a novel cystine-knot metallocarboxypeptidase inhibitor (chuPCI) was isolated from tubers of Solanum tuberosum, subsp. andigenum cv. Churqueña. Our results demonstrated that chuPCI is a member of the A/B-type family of metallocarboxypeptidases inhibitors. chuPCI was expressed and characterized by a combination of biochemical and mass spectrometric techniques. Direct comparison of the MALDI-TOF mass spectra for the native and recombinant molecules allowed us to confirm the presence of four different forms of chuPCI in the tubers. The majority of such forms have a molecular weight of 4309 Da and contain a cyclized Gln in the N-terminus. The other three forms are derived from N-terminal and/or C-terminal proteolytic cleavages. Taken together, our results contribute to increase the current repertoire of natural CKMPs.

Substrate specificity of human metallocarboxypeptidase D: Comparison of the two active carboxypeptidase domains.

Metallocarboxypeptidase D (CPD) is a membrane-bound component of the trans-Golgi network that cycles to the cell surface through exocytic and endocytic pathways. Unlike other members of the metallocarboxypeptidase family, CPD is a multicatalytic enzyme with three carboxypeptidase-like domains, although only the first two domains are predicted to be enzymatically active. To investigate the enzymatic properties of each domain in human CPD, a critical active site Glu in domain I and/or II was mutated to Gln and the protein expressed, purified, and assayed with a wide variety of peptide substrates. CPD with all three domains intact displays >50% activity from pH 5.0 to 7.5 with a maximum at pH 6.5, as does CPD with mutation of domain I. In contrast, the domain II mutant displayed >50% activity from pH 6.5-7.5. CPD with mutations in both domains I and II was completely inactive towards all substrates and at all pH values. A quantitative peptidomics approach was used to compare the activities of CPD domains I and II towards a large number of peptides. CPD cleaved C-terminal Lys or Arg from a subset of the peptides. Most of the identified substrates of domain I contained C-terminal Arg, whereas comparable numbers of Lys- and Arg-containing peptides were substrates of domain II. We also report that some peptides with C-terminal basic residues were not cleaved by either domain I or II, showing the importance of the P1 position for CPD activity. Finally, the preference of domain I for C-terminal Arg was validated through molecular docking experiments. Together with the differences in pH optima, the different substrate specificities of CPD domains I and II allow the enzyme to perform distinct functions in the various locations within the cell.

Erratum: Efficacy and tolerability of lacosamide for secondary epileptic seizures in patients with brain tumor: A multicenter, observational retrospective study.

[This corrects the article DOI: 10.3892/ol.2017.5988.].

Efficacy and tolerability of lacosamide for secondary epileptic seizures in patients with brain tumor: A multicenter, observational retrospective study.

The present observational, multicenter, retrospective study investigated the efficacy and tolerability of lacosamide in controlling secondary epileptic seizures in patients with brain tumors in Spain. Data from the medical records of patients ≥18 years of age with brain tumors, who had received at least one dose of lacosamide for seizure management between July 2013 and November 2013, were collected. The primary and secondary objectives of the present study were to assess the effectiveness and tolerability of lacosamide. Data from 39 patients (mean age, 54.1 years; 66.7% male) were collected, where the two main reasons for initiation of lacosamide treatment were the lack of efficacy of other antiepileptic drugs (in 76.9% of patients) and the presence of adverse events (12.8%) associated with other antiepileptic drugs. At the initiation of treatment, patients received a mean lacosamide dose of 138.5±68.3 mg/day. At 6 months, lacosamide had significantly reduced the mean number of seizures from 26.4 (standard deviation [SD], 50.4) seizures for the 6 months prior to lacosamide initiation to a mean of 9.4 (SD, 22.8) seizures during the 6 months subsequent to lacosamide initiation; P<0.001. Lacosamide was generally well tolerated; of the 25 patients who had complete safety data available at a 6-month follow-up, 3 patients (12%) reported an adverse event, including dizziness, asthenia, instability and irritability. The present retrospective analysis suggested that lacosamide is an effective and well-tolerated treatment in patients experiencing seizures due to brain tumors. Additional prospective studies with a larger patient population and randomized trial design are warranted.

Conserved effects and altered trafficking of Cetuximab antibodies conjugated to gold nanoparticles with precise control of their number and orientation.

Gold nanoparticles (17 nm) have been functionalized with the antiangiogenic monoclonal antibody drug Cetuximab at a well-defined orientation and coverage density of antibodies. Functionalization has been carried out through site-directed chemistry via the selective oxidation of the carbohydrate moiety of antibodies linked to a thiolated hydrazide. A431 tumor cells have been exposed to these conjugates for in vitro evaluation of their effects. In addition to epithelial growth factor receptor blocking, trafficking and signaling alterations were also observed. Thus, the blocking effects of Cetuximab were increased and sustained for a longer time when associated with the nanoparticles. Enhancing antibody therapy effects by decreasing the needed dose and prolonging its effect by avoiding receptor recycling may serve to obtain increased therapeutic benefits for immunotherapy.

First-line use of rituximab correlates with increased overall survival in late post-transplant lymphoproliferative disorders: retrospective, single-centre study.

This retrospective study evaluates the impact of rituximab on PTLD response and survival in a single-centre cohort. PTLD cases between 1984 and 2009, including heart, kidney, liver and lung transplant recipients, were included. Survival was analysed taking into account the type of PTLD (monomorphic vs. polymorphic), EBV infection status, IPI score, Ann Arbor stage and use of rituximab. Among 1335 transplanted patients, 24 developed PTLD. Median age was 54 yr (range 29-69), median time to diagnosis 50 months (range 0-100). PTLD type was predominantly late/monomorphic (79% and 75%), mostly diffuse large B-cell type. Overall response rate (ORR) was 62% (66% rituximab vs. 50% non-rituximab; P = 0.5). R-CHOP-like regimens were used most frequently (72% of patients treated with rituximab). Median overall survival was 64 months (CI 95% 31-96). OS was significantly increased in patients treated with rituximab (P = 0.01; CI 95% rituximab 58-79 months; non-rituximab 1-30 months). Post-transplant immunosuppression regimen had no effect on survival or time to PTLD, except for cyclosporine A (CyA), which associated with increased time to PTLD (P = 0.02). Rituximab was associated with increased survival in our single-centre series, and it should be considered as first-line therapy for PTLD patients. The possible protective effect of CyA for development of PTLD should be prospectively evaluated.

Index lesion characterization by (11)C-Choline PET/CT and Apparent Diffusion Coefficient parameters at 3 Tesla MRI in primary prostate carcinoma.

BACKGROUND: Index lesion characterization is important in the evaluation of primary prostate carcinoma (PPC). The aim of this study was to analyze the contribution of (11) C-Choline PET/CT and the Apparent Diffusion Coefficient maps (ADC) in detecting the Index Lesion and clinically significant tumors in PPC. METHODS: Twenty-one untreated patients with biopsy-proven PPC and candidates for radical prostatectomy (RP) were prospectively evaluated by means of Ultra-High Definition PET/CT and 3T MRI, which included T2-weighted imaging (T2WI) and ADC maps obtained from diffusion weighted imaging (DWI). Independent experts analyzed all the images separately and were unaware of the pathological data. In each case, the Index lesion was defined as the largest tumor measured on histopathology (Index H). In addition, the largest lesion observed on MRI (Index MRI) and the highest avid (11) C-Choline uptake lesion (Index PET) were obtained. The Gleason scores (GS) of the tumors were determined. PET/CT and ADC map quantitative parameters were also calculated. Measures of correlation among imaging parameters as well as the sensitivity (S), specificity (Sp), negative and positive predictive values (NPV and PPV) for tumor detection were analyzed. All data was validated with the pathological study. RESULTS: In the morphological study, 139 foci of carcinoma were identified, 47 of which corresponded to clinically significant tumors (>0.5 cm(3)). The remaining foci presented a maximum diameter (dmax ) of 0.1 cm ± SD 0.75 and were not classified as clinically significant. Thirty-two tumors presented a GS (3 + 3), nine GS (3 + 4), and six GS (4 + 3). A total of 21 Index H (dmax = 1.37 cm SD ± 0.61) were identified. The S, Sp, NPV, and PPV for tumor detection with PET were 100%, 70%, 83%, 100%, and for MRI were 46%, 100%, 100%, 54%, respectively. Both Index PET and Index MRI were complementary and identified 95% of the Index H when quantitative criteria were used. CONCLUSION: In spite of the fact that PET imaging has higher tumor sensitivity than MRI, (11) C-Choline PET and ADC maps have complementary roles in the evaluation of Index Lesion in PPC. Index PET and Index MRI could be complementary targets in the therapeutic planning of PPC.

Biochemical characterization of a novel carboxypeptidase inhibitor from a variety of Andean potatoes.

Natural protease inhibitors of metallocarboxypeptidases are rarely reported. In this work, the cloning, expression and characterization of a proteinaceous inhibitor of the A/B-type metallocarboxypeptidases, naturally occurring in tubers of Solanum tuberosum, subsp. andigenum cv. Imilla morada, are described. The obtained cDNA encoded a polypeptide of 80 residues, which displayed the features of metallocarboxypeptidase inhibitor precursors from the Potato Carboxypeptidase Inhibitor (PCI) family. The mature polypeptide (39 residues) was named imaPCI and in comparison with the prototype molecule of the family (PCI from S. tuberosum subsp. tuberosum), its sequence showed one difference at its N-terminus and another three located at the secondary binding site, a region described to contribute to the stabilization of the complex inhibitor-target enzyme. In order to gain insights into the relevance of the secondary binding site in nature, a recombinant form of imaPCI (rimaPCI) having only differences at the secondary binding site with respect to recombinant PCI (rPCI) was cloned and expressed in Escherichia coli. The rimaPCI exhibited a molecular mass of 4234.8Da by MALDI-TOF/MS. It displayed potent inhibitory activity towards A/B-type carboxypeptidases (with a Ki in the nanomolar range), albeit 2-4-fold lower inhibitory capacity compared to its counterpart rPCI. This result is in agreement with our bioinformatic analysis, which showed that the main interaction established between the secondary binding site of rPCI and the bovine carboxypeptidase A is likely lost in the case of rimaPCI. These observations reinforce the importance of the secondary binding site of PCI-family members on inhibitory effects towards A/B-type metallocarboxypeptidases. Furthermore, as a simple proof of concept of its applicability in biotechnology and biomedicine, the ability of rimaPCI to protect human epidermal growth factor from C-terminal cleavage and inactivation by carboxypeptidases A and B was demonstrated.