Structural basis for expanded substrate specificities of human long chain acyl-CoA dehydrogenase and related acyl-CoA dehydrogenases.

Crystal structures of human long-chain acyl-CoA dehydrogenase (LCAD) and the catalytically inactive Glu291Gln mutant, have been determined. These structures suggest that LCAD harbors functions beyond its historically defined role in mitochondrial ß-oxidation of long and medium-chain fatty acids. LCAD is a homotetramer containing one FAD per 43 kDa subunit with Glu291 as the catalytic base. The substrate binding cavity of LCAD reveals key differences which makes it specific for longer and branched chain substrates. The presence of Pro132 near the start of the E helix leads to helix unwinding that, together with adjacent smaller residues, permits binding of bulky substrates such as 3α, 7α, l2α-trihydroxy-5ß-cholestan-26-oyl-CoA. This structural element is also utilized by ACAD11, a eucaryotic ACAD of unknown function, as well as bacterial ACADs known to metabolize sterol substrates. Sequence comparison suggests that ACAD10, another ACAD of unknown function, may also share this substrate specificity. These results suggest that LCAD, ACAD10, ACAD11 constitute a distinct class of eucaryotic acyl CoA dehydrogenases.

Structural Basis for Expanded Substrate Specificities of Human Long Chain Acyl-CoA Dehydrogenase and Related Acyl- CoA Dehydrogenases.

Crystal structures of human long-chain acyl-CoA dehydrogenase (LCAD) and the E291Q mutant, have been determined. These structures suggest that LCAD harbors functions beyond its historically defined role in mitochondrial ß-oxidation of long and medium-chain fatty acids. LCAD is a homotetramer containing one FAD per 43kDa subunit with Glu291 as the catalytic base. The substrate binding cavity of LCAD reveals key differences which makes it specific for longer and branched chain substrates. The presence of Pro132 near the start of the E helix leads to helix unwinding that, together with adjacent smaller residues, permits binding of bulky substrates such as 3α, 7α, l2α-trihydroxy-5ß-cholestan-26-oyl-CoA. This structural element is also utilized by ACAD11, a eucaryotic ACAD of unknown function, as well as bacterial ACADs known to metabolize sterol substrates. Sequence comparison suggests that ACAD10, another ACAD of unknown function, may also share this substrate specificity. These results suggest that LCAD, ACAD10, ACAD11 constitute a distinct class of eucaryotic acyl CoA dehydrogenases.

Chronic Kidney Disease in Patients with Psoriasis -A Hospital Based Cross Sectional Study.

BACKGROUND: Psoriasis is a multi-system inflammatory disease where skin and joints are the primary targets. Recently, some studies had shown the association of psoriasis with kidney disease. AIMS: To study the association of psoriasis with chronic kidney disease (CKD) in a tertiary health care center. METHODOLOGY: The study was conducted in the Department of Dermatology in a tertiary care center in Kerala. The study was a descriptive cross-sectional study for 6 months from August 2017 to January 2018. A total of 104 patients with psoriasis were studied. Clinical data was collected. Glomerular filtration rate (GFR) and albumin creatinine ratio (ACR) were found out to know the presence of CKD. Descriptive and inferential statistical analysis has been carried out in the present study. OBSERVATIONS: Of the 104 patients, 14 were diagnosed as having CKD. Of the 14 CKD patients, 12 had severe psoriasis, 2 had moderate psoriasis, and none had mild psoriasis. The risk factors for CKD (presence of diabetes mellitus/hypertension or intake of drugs-non-steroidal anti-inflammatory drugs [NSAIDs]/cyclosporine) were present in 9 out of 14 CKD patients. The duration of psoriasis was more than 10 years in 10 CKD patients. CONCLUSION: Our study demonstrated that psoriatic patients have an increased risk of developing CKD and this risk is found to increase with the severity and duration of psoriasis. Our results require confirmation in large-patient populations in prospective studies or case-control studies.

Automatic implementation of precise grid screens: the four-corners method.

Crystallization trials can be designed as a systematic gradient of the concentration of key reagents and/or pH centered on the original conditions. While the concept of the grid screen is simple, its implementation is tedious and difficult by hand. A procedure has been developed for preparing crystallization grid screens that is both efficient and achieves high accuracy because it relies on a limited number of solutions that are carefully prepared by hand. The ;four-corners' approach to designing grid screens uses the minimum and maximum concentrations of the components being varied in the grid screen as the sole stock solutions. For an N-dimensional grid only 2(N) corner solutions require detailed preparation, making the screens efficient. Furthermore, by keeping the concentrations as tight as possible to the grid, the potential impact of pipette errors is minimized, creating a highly precise screen.

Experimental evidence for a metallohydrolase mechanism in which the nucleophile is not delivered by a metal ion: EPR spectrokinetic and structural studies of aminopeptidase from Vibrio proteolyticus.

Metallohydrolases catalyse some of the most important reactions in biology and are targets for numerous chemotherapeutic agents designed to combat bacterial infectivity, antibiotic resistance, HIV infectivity, tumour growth, angiogenesis and immune disorders. Rational design of inhibitors of these enzymes with chemotherapeutic potential relies on detailed knowledge of the catalytic mechanism. The roles of the catalytic transition ions in these enzymes have long been assumed to include the activation and delivery of a nucleophilic hydroxy moiety. In the present study, catalytic intermediates in the hydrolysis of L-leucyl-L-leucyl-L-leucine by Vibrio proteolyticus aminopeptidase were characterized in spectrokinetic and structural studies. Rapid-freeze-quench EPR studies of reaction products of L-leucyl-L-leucyl-L-leucine and Co(II)-substituted aminopeptidase, and comparison of the EPR data with those from structurally characterized complexes of aminopeptidase with inhibitors, indicated the formation of a catalytically competent post-Michaelis pre-transition state intermediate with a structure analogous to that of the inhibited complex with bestatin. The X-ray crystal structure of an aminopeptidase-L-leucyl-L-leucyl-L-leucine complex was also analogous to that of the bestatin complex. In these structures, no water/hydroxy group was observed bound to the essential metal ion. However, a water/hydroxy group was clearly identified that was bound to the metal-ligating oxygen atom of Glu152. This water/hydroxy group is proposed as a candidate for the active nucleophile in a novel metallohydrolase mechanism that shares features of the catalytic mechanisms of aspartic proteases and of B2 metallo-beta-lactamases. Preliminary studies on site-directed variants are consistent with the proposal. Other features of the structure suggest roles for the dinuclear centre in geometrically and electrophilically activating the substrate.

A retrospective study of the pattern of sexually transmitted diseases during a ten-year period.

BACKGROUND: Proper knowledge of the patterns of sexually transmitted diseases (STDs) in different geographical regions is necessary for evolving proper strategies for control of these diseases. AIMS: To study the pattern of STDs and to analyze the changes during a ten-year period from 1990 among patients attending Medical College Hospital, Kottayam. METHODS: Case records of 686 patients with STDs who attended the outpatient wing of the Department of Dermatology and Venereology were studied. RESULTS: There were 504 males and 182 females in the total of 686 patients. Marital contact alone was reported by 123 (67.6%) female patients. Genital ulcer diseases (GUDs) accounted for the maximum number of STDs, with 504 cases (73.5%), followed by condyloma acuminatum (17.5%) and gonorrhea (10.1%). Forty-three patients had multiple infections. The total number of patients during the first year of study was 129, while it was 41 during the last year. Bacterial STDs showed a striking reduction in numbers. The decline was less marked in the case of viral STDs. CONCLUSION: The majority of patients had genital ulcer diseases. Spouses were the most common source of infection for female patients. There was a marked decline in the number of patients with various STDs during the ten-year period. The decline was more evident in the bacterial STDs resulting in an apparent increase of the viral STDs towards the end of the period of study.

Not just skin deep: a case report of multiple endocrine neoplasia type 1.

Multiple endrocrine neoplasia (MEN) type 1 is characterized by mainly a triad of pancreatic, pituitary and parathyroid involvement. This is a case report of a 41-year-old male in whom recognition of collagenoma and gingival papule led to the identification of MEN type 1. Often the recognition of such dermatological manifestations help in the presymptomatic diagnosis of complex syndromes.

The effect of a Glu370Asp mutation in glutaryl-CoA dehydrogenase on proton transfer to the dienolate intermediate.

We have determined steady-state rate constants and net rate constants for the chemical steps in the catalytic pathway catalyzed by the E370D mutant of glutaryl-CoA dehydrogenase and compared them with those of the wild-type dehydrogenase. We sought rationales for changes in these rate constants in the structure of the mutant cocrystallized with the alternate substrate, 4-nitrobutyric acid. Substitution of aspartate for E370, the catalytic base, results in a 24% decrease in the rate constant for proton abstraction at C-2 of 3-thiaglutaryl-CoA as the distance between C-2 of the ligand and the closest carboxyl oxygen at residue 370 increases from 2.9 A to 3.1 A. The net rate constant for flavin reduction due to hydride transfer from C-3 of the natural substrate, which includes proton abstraction at C-2, to N5 of the flavin decreases by 81% due to the mutation, although the distance increases only by 0.7 A. The intensities of charge-transfer bands associated with the enolate of 3-thiaglutaryl-CoA, the reductive half-reaction (reduced flavin with oxidized form of substrate), and the dienolate following decarboxylation are considerably diminished. Structural investigation suggests that the increased distance and the change in angle of the S-C1(=O)-C2 plane of the substrate with the isoalloxazine substantially alter rates of the reductive and oxidative half-reactions. This change in active site geometry also changes the position of protonation of the four carbon dienolate intermediate to produce kinetically favorable product, vinylacetyl-CoA, which is further isomerized to the thermodynamically stable normal product, crotonyl-CoA.

Malignant acanthosis nigricans with occult primary.

A case of generalized malignant acanthosis nigricans of 2 years duration is reported. In spite of the long duration of this cutaneous marker of internal malignancy, the patient was completely asymptomatic and extensive investigations revealed the presence of widespread metastasis of mucin secreting signet cell adenocarcinoma from an unknown primary site. In addition the patient also had acquired hypertrichosis lanuginose and florid cutaneous papillomatosis which are also markers of internal malignancy.

A retrospective study of the pattern of sexually transmitted diseases during a ten-year period.

BACKGROUND: Proper knowledge of the patterns of sexually transmitted diseases (STDs) in different geographical regions is necessary for evolving proper strategies for control of these diseases. AIMS: To study the pattern of STDs and to analyze the changes during a ten-year period from 1990 among patients attending Medical College Hospital, Kottayam. METHODS: Case records of 686 patients with STDs who attended the outpatient wing of the Department of Dermatology and Venereology were studied. RESULTS: There were 504 males and 182 females in the total of 686 patients. Marital contact alone was reported by 123 (67.6%) female patients. Genital ulcer diseases (GUDs) accounted for the maximum number of STDs, with 504 cases (73.5%), followed by condyloma acuminatum (17.5%) and gonorrhea (10.1%). Forty-three patients had multiple infections. The total number of patients during the first year of study was 129, while it was 41 during the last year. Bacterial STDs showed a striking reduction in numbers. The decline was less marked in the case of viral STDs. CONCLUSION: The majority of patients had genital ulcer diseases. Spouses were the most common source of infection for female patients. There was a marked decline in the number of patients with various STDs during the ten-year period. The decline was more evident in the bacterial STDs resulting in an apparent increase of the viral STDs towards the end of the period of study.

Malignant acanthosis nigricans with occult primary.

A case of generalized malignant acanthosis nigricans of 2 years duration is reported. In spite of the long duration of this cutaneous marker of internal malignancy, the patient was completely asymptomatic and extensive investigations revealed the presence of widespread metastasis of mucin secreting signet cell adenocarcinoma from an unknown primary site. In addition the patient also had acquired hypertrichosis lanuginose and florid cutaneous papillomatosis which are also markers of internal malignancy.