Gene/Protein Disease Symptom Drug Enzyme Compound
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Query: UMLS:C0027960 (mole)
 21,279 document(s) hit in 31,850,051 MEDLINE articles (0.00 seconds)

A guinea pig liver transglutaminase (G-TGase)-mediated procedure for the site-specific modification of chimeric proteins was recently reported. Here, an alternative method with advantages over the recent approach is described. This protocol utilizes a microbial transglutaminase (M-TGase) instead of the G-TGase as the catalyst. M-TGase, which has rather broad structural requirements as compared to the G-TGase, tends to catalyze an acyl transfer reaction between the gamma-carboxamide group of a intact protein-bound glutamine residue and various primary amines. To demonstrate the applicability of the M-TGase-catalyzed protein modification in a drug delivery system, we have utilized recombinant human interleukin 2 (rhIL-2) as the target protein and two synthetic alkylamine derivatives of poly(ethyleneglycol) (PEG12; MW 12 kDa) and galactose-terminated triantennary glycosides ((Gal)(3))) as the modifiers. For the M-TGase-catalyzed reaction with PEG12 and (Gal)(3), 1 mol of alkylamine was incorporated per mole of rhIL-2, respectively. Peptide mapping of (Gal)(3)-modified rhIL-2 ((Gal)(3)-rhIL-2) by liquid chromatography-electrospray ionization mass spectrometry (LC-ESI/MS) suggested that the Gln74 residue in rhIL-2 was site specifically modified with (Gal)(3). The PEG12-rhIL-2 and (Gal)(3)-rhIL-2 conjugates retained full bioactivity relative to the unmodified rhIL-2. In pharmacokinetic studies, PEG12-rhIL-2 was eliminated more slowly from the circulation than rhIL-2, whereas (Gal)(3)-rhIL-2 accumulated in the liver via hepatic asialoglycoprotein receptor binding. The results of this study expand the applicability of the TGase-catalyzed methodology for the preparation of protein conjugates for clinical use.
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PMID:Further studies on the site-specific protein modification by microbial transglutaminase. 1156 88

Transglutaminases (TGases) catalyze several reactions with protein substrates, including formation of gamma-glutamyl-epsilon-lysine cross-links and gamma-glutamylpolyamine residues. The resulting gamma-glutamylamines are excised intact during proteolysis. TGase activity is altered in several diseases, highlighting the importance of in situ enzymatic determinations. Previous work showed that TGase activity (as measured by an in vitro assay) and free gamma-glutamyl-epsilon-lysine levels are elevated in Huntington disease (HD) and that gamma-glutamyl-epsilon-lysine is increased in HD CSF. Although free gamma-glutamyl-epsilon-lysine was used in these studies as an index of in situ TGase activity, gamma-glutamylpolyamines may also be diagnostic. We have devised methods for the simultaneous determination of four gamma-glutamylamines in CSF: gamma-glutamyl-epsilon-lysine, gamma-glutamylspermidine, gamma-glutamylputrescine, and bis-gamma-glutamylputrescine and showed that all are present in normal human CSF at concentrations of approximately 150, 670, 40, and 240 nM, respectively. The high gamma-glutamylspermidine/gamma-glutamylputrescine and gamma-glutamylspermidine/bis-gamma-glutamylputrescine ratios presumably reflect in part the large spermidine to putrescine mole ratio in human brain. We also showed that all four gamma-glutamylamines are elevated in HD CSF. Our findings support the hypotheses that (i) gamma-glutamylpolyamines are reflective of TGase activity in human brain, (ii) polyamination is an important post-translational modification of brain proteins, and (iii) TGase-catalyzed modification of proteins is increased in HD brain.
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PMID:Increased levels of gamma-glutamylamines in Huntington disease CSF. 1842 43