Has activity against the synthetic substrates Boc-Phe-Ser-Arg-Mec, Boc-Leu-Thr-Arg-Mec, Boc-Gln-Ala-Arg-Mec and Boc-Val-Pro-Arg-Mec. The single-chain form is more active than the two-chain form against all of these substrates.
Biochem. J. 303 ( Pt 1), 187-190 (1994)[PubMed:7945238]
It has previously been reported that two kinds of human gastric adenocarcinoma cell lines (STKM-1 and MKN28) secrete a trypsin-like enzyme. In this study, four molecular forms of the enzyme (26, 25, 24 and 23 kDa on non-reducing SDS/PAGE) were purified from the serum-free conditioned medium of STKM-1 cells. Analysis of N-terminal amino acid sequences showed that the 26 kDa protein was a two-chain form of trypsinogen 1 which had been produced by proteolytic cleavage of the Arg107-Val108 bond of trypsinogen 1, and the 24 kDa protein was the one-chain form of trypsinogen 1. The 25 and 23 kDa proteins were the activated forms of the two-chain and one-chain trypsinogen 1 respectively. Isoelectric focusing gave pI values of 6.3 and 6.6 for the 26 kDa two-chain form and the 24 kDa one-chain form of trypsinogen 1 respectively. Comparison of the proteolytic activities indicated that the one-chain trypsin 1 had amidolytic activity about four times higher than that of the two-chain enzyme.
Catalysis of the hydrolysis of internal, alpha-peptide bonds in a polypeptide chain by a catalytic mechanism that involves a catalytic triad consisting of a serine nucleophile that is activated by a proton relay involving an acidic residue (e.g. aspartate or glutamate) and a basic residue (usually histidine).
Hereditary pancreatitis (HP) is a rare, early-onset genetic disorder characterized by epigastric pain and often more serious complications. We now report that an Arg-His substitution at residue 117 of the cationic trypsinogen gene is associated with the HP phenotype. This mutation was observed in all HP affected individuals and obligate carriers from five kindreds, but not in individuals who married into the families nor in 140 unrelated individuals. X-ray crystal structure analysis, molecular modelling, and protein digest data indicate that the Arg 117 residue is a trypsin-sensitive site. Cleavage at this site is probably part of a fail-safe mechanism by which trypsin, which is activated within the pancreas, may be inactivated; loss of this cleavage site would permit autodigestion resulting in pancreatitis.
The whole of the physical, chemical, and biochemical processes carried out by multicellular organisms to break down ingested nutrients into components that may be easily absorbed and directed into metabolism.
Tyr-154 was proposed to be phosphorylated (PubMed8683601) but it has been shown (PubMed17087724) to be sulfated instead. Phosphate and sulfate groups are similar in mass and size, and this can lead to erroneous interpretation of the results.
The X-ray structure of human trypsin 1 has been determined in the presence of diisopropyl-phosphofluoridate by the molecular replacement method and refined at a resolution of 2.2 A to an R-factor of 18%. Crystals belong to the space group P4, with two independent molecules in the asymmetric unit packing as crystallographic tetramers. This study was performed in order to seek possible structural peculiarities of human trypsin 1, suggested by some striking differences in its biochemical behavior as compared to other trypsins of mammalian species. Its fold is, in fact, very similar to those of the bovine, rat and porcine trypsins, with root-mean-square differences in the 0.4 to 0.6 A range for all 223 C alpha positions. The most unexpected feature of the human trypsin 1 structure is in the phosphorylated state of tyrosine residue 151 in the present X-ray study. This feature was confirmed by mass spectrometry on the same inhibited sample and also on the native enzyme. This phosphorylation strengthens the outstanding clustering of highly negative or highly positive electrostatic surface potentials. The peculiar inhibitory behaviour of pancreatic secretory trypsin inhibitors of the Kazal type on this enzyme is discussed as a possible consequence of these properties. A charged surface loop has also been interpreted as an epitope site recognised by a monoclonal antibody specific to human trypsin 1.
The crystal structure of human pancreatic cationic trypsin showed the chemical modification of Tyr154, which was originally described as phosphorylation [Gaboriaud C, Serre L, Guy-Crotte O, Forest E & Fontecilla-Camps JC (1996) J Mol Biol259, 995-1010]. Here we report that Tyr154 is sulfated, not phosphorylated. Cationic and anionic trypsinogens were purified from human pancreatic juice and subjected to alkaline hydrolysis. Modified tyrosine amino acids were separated on a Dowex cation-exchange column and analyzed by thin layer chromatography. Both human cationic and anionic trypsinogens contained tyrosine sulfate, but no tyrosine phosphate, whereas bovine trypsinogen contained neither. Furthermore, incorporation of [(35)S]SO(4) into human cationic trypsinogen transiently expressed by human embryonic kidney 239T cells was demonstrated. Mutation of Tyr154 to Phe abolished radioactive sulfate incorporation, confirming that Tyr154 is the site of sulfation in cationic trypsinogen. Sulfated pancreatic cationic trypsinogen exhibited faster autoactivation than a nonsulfated recombinant form, suggesting that tyrosine sulfation of trypsinogens might enhance intestinal digestive zymogen activation in humans. Finally, sequence alignment revealed that the sulfation motif is only conserved in primate trypsinogens, suggesting that typsinogen sulfation is absent in other vertebrates.
Protein involved in the process whereby nutrients are rendered soluble and capable of being absorbed by the organism or cell, by action of various hydrolytic enzymes that break down proteins, carbohydrates, fats, etc.
Enzyme which catalyzes hydrolysis reaction, i.e. the addition of the hydrogen and hydroxyl ions of water to a molecule with its consequent splitting into two or more simpler molecules.
Proteolytic enzyme with a serine residue (Ser) in its active site. The reactivity of the serine residue is ensured by the vicinity of a histidine and an aspartate residue (catalytic triad), all three residues are required for the charge relay system to take place.
A reference proteome is a set of protein sequences derived from a complete proteome which constitutes a defined standard for a particular user community. Reference proteomes are manually defined according to a number of criteria. They cover the proteomes of well- studied model organisms and other proteomes of interest for biomedical and biotechnological research. Reference proteomes have been selected to provide broad coverage of the tree of life, and constitute a representative cross-section of the taxonomic diversity to be found within UniProtKB.
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