Oligo(methionyl) proteins

Abstract

A number of model isopeptides containing oligo(methionine) chains varying in length (2 -5 residues) covalently linked to the &-amino group of lysine were synthesized by solid-phase procedures. Hydrolysis of these peptides by pepsin, chymotrypsin, cathepsin C (dipeptidyl peptidase IV) and intestinal aminopeptidase N was investigated using high-performance liquid chromatography to identify and quantify the hydrolysis products. Methionine oligomers grafted onto lysine were cleaved to tripeptides by pepsin. Chymotrypsin preferentially hydrolyzed the methionyl-methionine bond preceding the isopeptide bond. Cathepsin C released dimethionyl units from the covalently attached polymers. Intestinal aminopeptidase caused efficient hydrolysis of both peptides and isopeptide bonds although free methionine decreased the cleavage of the latter bond. Hydrophobic characteristics of oligo(methionine) chains promoted enzyme-catalyzed transpeptidations resulting probably from acyl-transfertype reactions. Complementary hydrolysis of the isopeptides by these digestive enzymes suggests that covalent attachment of oligo(amino acid)s to food proteins may improve their nutritional value.

Hydrolysis of poly-L-methionyl proteins by some enzymes of the digestive tract

“…AZ-Hydroxysuccinimide ester of a-[(ter£-butyloxy)carbonyl]-L-methionine as well as the L forms of Met2 and Met3 were supplied by Bachem Fine Chemicals, Bubendorf, Switzerland. Synthesis of Met4 and Mets was carried out by the solid-phase procedure (Barany and Merrifield, 1980) as detailed by Gaertner and Puigserver (1984b). Chymotrypsin, trypsin, and pepsin were from Worthington Biochemical Corp., Freehold, NJ, whereas elastase was from Boehringer, Mannheim, FRG.…”

“…The aim of this study was to determine in vitro digestibility of casein modified by using the iV-carboxy anhydride method under different experimental conditions and subsequent availability of the polymerized methionine. To determine the hydrolytic processes for covalently linked polymethionine chains, digestions with a number of individual enzymes were carried out and the resulting data compared to those previously obtained with the synthetic model isopeptides N'-oligo-L-methionyl-L-lysine (Gaertner and Puigserver, 1984b).…”

Biocatalysis in Polymer-Supported Synthesis: Enzyme-Labile Linker Groups

“…[19] Furthermore, enzymatic hydrolysis of model isopeptides N e -oligo(l-methionyl)-l-lysine from Biobeads [20] by pepsin, chymotrypsin, cathepsin C (dipeptidyl peptidase IV), and intestinal aminopeptidase N was investigated using high-performance liquid chromatography to identify and quantify the hydrolysis products. [21] Larsen et al reported the enzymatic cleavage of a desB30 insulin B-chain from a presequence [Lys(Boc)] 6 . This spacer shifts the conformation of the growing peptide chain from a b-structure to a random coil conformation and reduces peptide-chain aggregation, which otherwise causes serious synthetic problems.…”

Absorption of Oligo-L-[35S]methionine after Feeding of a Low Casein or a Low Soybean Protein Isolate Diet in Rats

“…Dietary proteins are known to potentiate the exocrine pancreatic secretion in the rats (12,13). Gaertner and Puigserver (16,17) reported that oligo-Lmethionine is digested by pepsin in vitro, which suggests that the gastric digestion of OM is one of the possible mechanisms affecting the difference in the absorptive efficiency of OM between the casein and SPI groups. We also demonstrated the small intestinal transit is faster after the feeding of a low SPI diet than a low casein diet ( 15).…”