gamma-Glutamylamine derivatives in isolated rat hepatocyte proteins.
Freshly isolated rat hepatocytes were found to contain a 3-fold higher level of putrescine than perfused liver. The bulk of this diamine was recovered in the acid-insoluble fraction of the cell. In order to determine the nature of the amine binding, the levels of gamma-glutamylamine derivatives were measured. The method used involves exhaustive proteolytic digestion of the acid-insoluble fraction of hepatocytes, followed by ion-exchange chromatography. For N1-(gamma-glutamyl)putrescine, a combined ion-exchange chromatographic and reverse-phase h.p.l.c. procedure was adopted. This allowed for the direct detection of less than 50 pmol of this derivative in enzymic hydrolysates. Several of the gamma-glutamylamines reported previously [Beninati, Piacentini, Argento-Ceru', Russo-Caia & Autuori (1985) Biochim. Biophys. Acta 841, 120-126] in the whole organ were found in the isolated liver cells. The elevated level of N1-(gamma-glutamyl)putrescine and the absence of bis-(gamma-glutamyl)spermine was noteworthy. The results suggest that, in rat hepatocytes, both polyamine-dependent post-translational modification of some proteins and cross-linking between proteins involving the glutamine and lysine residues occurs.
Piacentini
M
M
Department of Biology, 2nd University of Rome Tor Vergata, Italy.
Beninati
S
S
D000818:Animals; D002851:Chromatography, High Pressure Liquid; D002852:Chromatography, Ion Exchange; D004151:Dipeptides / Q000032:analysis; D006868:Hydrolysis; D008099:Liver / Q000032:analysis*; D011073:Polyamines / Q000032:analysis* / Q000302:isolation & purification; D011506:Proteins; D011700:Putrescine / Q000031:analogs & derivatives / Q000032:analysis; D051381:Rats; D011919:Rats, Inbred Strains; D013095:Spermidine / Q000031:analogs & derivatives / Q000032:analysis; D013096:Spermine / Q000031:analogs & derivatives / Q000032:analysis
D004151:Dipeptides; D011073:Polyamines; D011506:Proteins; C001299:epsilon-(gamma-glutamyl)-lysine; D013096:Spermine; C011830:glutamylputrescine; C055362:N(1)-(gamma-glutamyl)spermine; C055363:N(1)-(gamma-glutamyl)spermidine; D013095:Spermidine; D011700:Putrescine