In vivo utilization of cystine-containing synthetic short-chain peptides after intravenous bolus injection in the rat.
For the first time, in vivo utilization of two highly soluble and stable cystine-containing synthetic short-chain peptides, bis-L-alanyl-L-cystine and bis-glycyl-L-cystine, were investigated in adult rats. Within 5 min after an intravenous bolus, blood samples were drawn (inferior vena cava) and plasma amino acid and peptide levels were determined using RP-HPLC (precolumn derivatization with 5-dimethylaminonaphthalene-1-sulfonylchloride). Both peptides were rapidly cleared from plasma (estimated elimination t1/2: 4 min for the glycyl peptide and less than 2 min for the alanyl peptide). The initial high amounts of mono-L-alanyl-L-cystine and mono-glycyl-L-cystine as well as the prompt increase of the constituent free amino acids alanine, glycine and cystine strongly suggest that the peptide disappearance is mainly due to a very fast two-step hydrolysis in the extracellular compartment, presumably catalyzed by soluble and/or plasma membrane-bound peptidases. The observed rapid hydrolysis may serve as first evidence that short-chain peptides with C-terminal cystine residue may represent efficient sources of free cystine in parenteral nutrition.
Stehle
P
P
Institute for Biological Chemistry and Nutrition, University of Hohenheim, Stuttgart, West Germany.
Albers
S
S
Pollack
L
L
Fürst
P
P
D000409:Alanine / Q000097:blood; D000596:Amino Acids / Q000097:blood; D000818:Animals; D002851:Chromatography, High Pressure Liquid; D003553:Cystine / Q000008:administration & dosage / Q000493:pharmacokinetics*; D005998:Glycine / Q000097:blood; D006868:Hydrolysis; D007275:Injections, Intravenous; D008297:Male; D008657:Metabolic Clearance Rate; D010289:Parenteral Nutrition, Total; D010455:Peptides / Q000008:administration & dosage / Q000493:pharmacokinetics*; D051381:Rats; D011919:Rats, Inbred Strains
D000596:Amino Acids; D010455:Peptides; D003553:Cystine; D000409:Alanine; D005998:Glycine