Monitoring of Glycoprotein Quality Control System with a Series of Chemically Synthesized Homogeneous Native and Misfolded Glycoproteins.

The glycoprotein quality control (GQC) system in the endoplasmic reticulum (ER) effectively uses chaperone-type enzymes and lectins such as UDP-glucose:glycoprotein glucosyltransferase (UGGT), calnexin (CNX), calreticulin (CRT), protein disulfide bond isomerases (ERp57 or PDIs), and glucosidases to generate native-folded glycoproteins from nascent glycopolypeptides. However, the individual processes of the GQC system at the molecular level are still unclear. We chemically synthesized a series of several homogeneous glycoproteins bearing M9-high-mannose type oligosaccharides (M9-glycan), such as erythropoietin (EPO), interferon-ß (IFN-ß), and interleukin 8 (IL8) and their misfolded counterparts, and used these glycoprotein probes to better understand the GQC process. The analyses by high performance liquid chromatography and mass spectrometer clearly showed refolding processes from synthetic misfolded glycoproteins to native form through folding intermediates, allowing for the relationship between the amount of glucosylation and the refolding of the glycoprotein to be estimated. The experiment using these probes demonstrated that GQC system isolated from rat liver acts in a catalytic cycle regulated by the fast crosstalk of glucosylation/deglucosylation in order to accelerate refolding of misfolded glycoproteins.

Prospects in the total synthesis of protein therapeutics.

Protein therapeutics are gaining headway in the treatment and prevention of a variety of maladies. Critical to the success and growing use of biologic-level pharmaceuticals is the development of methods for their precise synthesis. This review highlights the emerging techniques for the total synthesis of proteins, with a special focus on the possibility of accessing therapeutic targets through chemoselective peptide ligations.

Chemical synthesis of homogeneous human glycosyl-interferon-ß that exhibits potent antitumor activity in vivo.

Chemical synthesis of homogeneous human glycoproteins exhibiting bioactivity in vivo has been a challenging task. In an effort to overcome this long-standing problem, we selected interferon-ß and examined its synthesis. The 166 residue polypeptide chain of interferon-ß was prepared by covalent condensation of two synthetic peptide segments and a glycosylated synthetic peptide bearing a complex-type glycan of biological origin. The peptides were covalently condensed by native chemical ligation. Selective desulfurization followed by deprotection of the two Cys(Acm) residues gave the target full-length polypeptide chain of interferon-ß bearing either a complex-type sialyl biantennary oligosaccharide or its asialo form. Subsequent folding with concomitant formation of the native disulfide bond afforded correctly folded homogeneous glycosyl-interferon-ß. The chemically synthesized sialyl interferon-ß exhibited potent antitumor activity in vivo.

Biopharmaceuticals and biosimilars in psoriasis: what the dermatologist needs to know.

The entry of biosimilar forms of biopharmaceutical therapies for the treatment of psoriasis and other immune-mediated disorders has provoked considerable interest. Although dermatologists are accustomed to the use of a wide range of generic topical agents, recognition of key differences between original agent (ie, the name brand) and the generic or biosimilar agent is necessary to support optimal therapy management and patient care. In this review we have summarized the current state of the art related to the impending introduction of biosimilars into dermatology. Biosimilars represent important interventions that are less expensive and hence offer the potential to deliver benefit to large numbers of patients who may not currently be able to access these therapies. But the development of biosimilars is not equivalent to that of small molecule generic therapies because of differences in molecular structure and processes of manufacture. The planned regulatory guidelines and path to approval may not encompass all of these potentially important differences and this may have clinical relevance to the prescriber and patient. Consequently, we have identified a series of key issues that should be considered to support the full potential of biosimilars for the treatment of psoriasis; ie, that of increased access to appropriate therapy for the psoriasis population worldwide.