Gene/Protein Disease Symptom Drug Enzyme Compound
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Query: EC:3.4.21.4 (trypsin)
 42,187 document(s) hit in 31,850,051 MEDLINE articles (0.00 seconds)

Pemphigus vulgaris antigen (PVA) is a member of the desmoglein subfamily of cadherin cell adhesion molecules. Because autoantibodies in this disease cause blisters due to loss of epidermal cell adhesion, and because desmoglein is found in the desmosome cell adhesion junction, we wanted to determine if PVA is also found in desmosomes. By immunofluorescence, PV IgG bound, in a dotted pattern, to the cell surface of cultured human keratinocytes induced to differentiate with calcium, suggesting junctional staining. However, by preembedding, immunogold electron microscopic studies only slight labeling could be detected in desmosomes, presumably because of difficulty in gold penetration of intact desmosomes. We therefore treated the keratinocytes with 0.01% trypsin in 1 mM calcium, conditions known to preserve cadherin antigenicity but that caused slight separation of desmosomes, before immunogold staining. In this case there was extensive labeling of the extracellular part of desmosomes but not of the interdesmosomal cell membrane which was stained with anti-beta 2-microglobulin antibodies. To confirm the specificity of this binding we showed that antibodies raised in rabbits against the extracellular portions of PVA also bound desmosomes in these cultures. In intact mouse epidermis we could also show slight, but specific, immunogold desmosomal labeling with PV IgG. Furthermore, neonatal mice injected with PV IgG affinity purified on PVA showed desmosomal separation with the IgG localized to desmosomal cores. These results indicate that PVA is organized and concentrated within the desmosome where it presumably functions to maintain the integrity of stratifying epithelia.
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PMID:Pemphigus vulgaris antigen, a desmoglein type of cadherin, is localized within keratinocyte desmosomes. 832 Feb 63

The primary structure of beta 2-microglobulin (beta 2m), the major constituent protein of beta 2-microglobulin amyloidosis (A beta 2m) or dialysis-amyloidosis, was initially shown to be identical to serum beta 2m, thereby strongly suggesting the polymerization of intact beta 2m in tissues. Recent biochemical data have been controversial, showing beta 2m acidic isoforms, fragmentation and amino acid sequence alteration of deposited beta 2m. The aim of this study was to reinvestigate beta 2m amyloid deposits for the presence of beta 2m fragments and/or amino acid sequence alteration. Four amyloid-laden tissues (3 femoral bone amyloid cysts and 1 heart tissue) from dialysis patients were used to isolate amyloidogenic beta 2m. Amyloid fibrils were isolated using the classic water extraction method, and purified in 6 M guanidine on a gel-filtration column. The protein was further purified on 17% SDS-PAGE gel, and transferred to a nitrocellulose membrane for immunostaining with antihuman beta 2m. beta 2m samples were microsequenced using the standard 03RPTH program on a 470A gas-phase sequencer, and HPLC was performed after digestion with trypsin. Two peaks were obtained with the gel filtration column, the second corresponding by molecular weight to beta 2m. SDS-PAGE analysis of this peak under reducing conditions, demonstrated one major band at 12,000 Da and a minor band at 25,000 Da (monomer and dimer), and no lower molecular weight bands were observed. The 12 kDa band was micro-sequenced and the amino acid sequence corresponded to that of normal beta 2m through the 40th residue. Amino acid sequence analysis showed no difference from normal beta 2m in any of the beta 2m proteins contained in the amyloid deposits isolated from the four studied tissues. Also, the HPLC profile of the four protein samples were strictly normal and identical to a commercial preparation of beta 2m. The present study demonstrates that beta 2m molecules polymerized in amyloid fibrils and deposits are intact and have a normal amino acid sequence, and produced by a specific and unique fibrillogenetic mechanism, which does not require proteolytic processing from the precursor protein to the amyloid fibrils.
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PMID:Polymerization of normal and intact beta 2-microglobulin as the amyloidogenic protein in dialysis-amyloidosis. 888 86

A crucial point to know in the prevention and treatment of beta 2-microglobulin (beta 2-m) amyloidosis is the putative resorption of amyloid fibrils in vivo. Although still controversial, long term clinical studies suggest that there is no resorption of amyloid fibrils in vivo, even after the suppression of the primary cause of amyloidosis. Two in vitro studies on murine and human AA amyloidosis as well as Alzheimer's disease suggest that protein constituents of amyloid fibrils may be resorbed. Protein resorption can be inhibited by the antiprotease amyloid P component. We extended these in vitro studies on beta 2-m amyloidosis, and assessed the effect of alpha 2-macroglobulin (alpha 2-M), a serum antiprotease previously found in this type of amyloidosis, on the putative protease induced protein resorption. Here, we show that amyloid proteins, beta 2-m and light chains of immunoglobulins, were degraded by trypsin. Preincubation of the amyloid proteins with alpha 2-M significantly inhibited the trypsin induced protein degradation of lambda chains. These data add further support to the hypothesis proposing a role for alpha 2-M and other antiproteases in the formation and/or persistence of beta 2-m amyloidosis.
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PMID:Alpha 2-macroglobulin protects some of the protein constituents of dialysis-associated amyloidosis from protease degradation. 907 Feb 17

Whey protein was digested with one of seven kinds of proteases at 37 degrees C (trypsin, proteinase K, actinase E, thermolysin, or papain) or at 25 degrees C (pepsin or chymotrypsin) for 24 h. The digested samples were assayed for the inhibitory activity of angiotensin-converting enzyme and for changes in the systolic blood pressure caused in spontaneously hypertensive rats after gastric intubation. The strongest depressive effect on the systolic blood pressure (-55 mm Hg) was observed at 6 h after gastric intubation of the whey protein that was digested by proteinase K. Finally, six peptides were chromatographically isolated from the proteinase K digest by a combination of hydrophobic reversed-phase HPLC and gel filtration. The amino acid sequences and their origins were clarified as follows: Val-Tyr-Pro-Phe-Pro-Gly [beta-casein (CN); f 59-64], Gly-Lys-Pro (beta 2-microglobulin; f 18-20), Ile-Pro-Ala (beta-lactoglobulin; f 78-80), Phe-Pro (serum albumin; f 221-222; beta-CN, f 62-63, f 157-158, and f 205-206), Val-Tyr-Pro (beta-CN; f 59-61), and Thr-Pro-Val-Val-Val-Pro-Pro-Phe-Leu-Gln-Pro (beta-CN; f 80-90). Chemical synthesis of these six peptides confirmed that all peptides, except an undecapeptide, have antihypertensive activity in spontaneously hypertensive rats. The synthetic tripeptide Ile-Pro-Ala, originating from beta-lactoglobulin, showed the strongest antihypertensive activity (-31 mm Hg).
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PMID:Structural analysis of new antihypertensive peptides derived from cheese whey protein by proteinase K digestion. 989 Dec 60


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