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)

Amyloid fibrils were isolated from cardiac tissue of two brothers who died from familial amyloidotic polyneuropathy (FAP) type II. Sequence analysis on peptides derived from proteolytic cleavage with trypsin and fragmentation with cyanogen bromide reveal that the fibril subunit protein is derived from plasma transthyretin (prealbumin). About two-thirds of the fibril subunit protein was found to contain an amino acid substitution at position 84 where the normal isoleucine residue has been replaced by serine. Sequence analysis of the plasma transthyretin (prealbumin) from the two brothers as well as two clinically diagnosed FAP type II family members and two of four children of affected individuals showed the presence of serine at position 84. The presence of this substitution also correlates with low serum levels of retinol-binding protein and thus transthyretin (prealbumin) position 84 may be involved with the interaction of these two proteins.
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PMID:Characterization of a transthyretin (prealbumin) variant associated with familial amyloidotic polyneuropathy type II (Indiana/Swiss). 376 Jan 89

Amyloid deposits in several heredofamilial forms of amyloidosis are chemically related to transthyretin (TTR, the protein usually referred to as prealbumin). A genetically abnormal TTR may be involved. Studies were conducted on TTR isolated from sera of patients with familial amyloidotic polyneuropathy (FAP), and on amyloid fibril protein (AFp) isolated from tissues of two Portuguese patients who died with FAP. AFp, purified by affinity chromatography on retinol-binding protein (RBP), resembled plasma TTR in forming a stable tetrameric structure, and in its binding affinities for both thyroxine and RBP. Purified AFp was found to comprise a TTR variant with a methionine for valine substitution at position 30. This conclusion was based upon studies that included: (i) comparative peptide mapping by reverse-phase high-performance liquid chromatography after trypsin digestion; (ii) cyanogen bromide (CNBr) cleavage studies; and (iii) amino acid microsequence analysis of selected tryptic and CNBr peptides. The variant TTR was also found to be present in serum samples from FAP patients, along with larger amounts of normal TTR. An effective, small-scale procedure was developed to determine whether or not the variant TTR was present in the plasma of an individual subject. This procedure involved isolation of TTR by affinity chromatography on RBP, followed by CNBr cleavage, and analysis for the presence of specific aberrant CNBr peptides. Studies with six kindreds, including 21 asymptomatic children of 6 patients with FAP, showed that the "abnormal" TTR can be detected and used as a preclinical marker of the disease in affected children of patients with FAP. It is likely that the variant TTR represents a point mutation within the TTR structural gene, and that the normal and mutant genes act as co-dominant alleles at a single locus in FAP. The distribution of the mutant TTR within the six families was consistent with the autosomal dominant mode of inheritance of FAP. The mutant TTR apparently selectively deposits in tissues as the amyloid characteristic of the disease.
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PMID:Family studies of the genetic abnormality in transthyretin (prealbumin) in Portuguese patients with familial amyloidotic polyneuropathy. 609 6

Amyloid fibril protein with a molecular weight of 8K daltons, in addition to one of 16K daltons, has been isolated and characterized from an autopsy sample of a patient with familial amyloid polyneuropathy in a Japanese family from Ogawa Village, Nagano Prefecture. The component was shown to react with an antiserum to normal plasma prealbumin, as did the other. Following the purification by reverse phase liquid chromatography, it was digested with trypsin and the peptides, after the purification by HPLC were sequenced. The data showed that the component was a distinct fragment whose sequence was identical with that of the residues from Gly-6 to Tyr-78 of the prealbumin, except that it had a methionine for a valine at position 25. This corresponded with the position 30 where a valine residues has been reported for the sequence of the normal plasma prealbumin.
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PMID:A variant prealbumin-related low molecular weight amyloid fibril protein in familial amyloid polyneuropathy of Japanese origin. 651 15

Prealbumin from an individual with heredofamilial amyloid polyneuropathy of Swedish origin was isolated from plasma by using a three-step procedure involving ion exchange, Affi-gel Blue affinity chromatography, and gel filtration. This prealbumin and its associated amyloid fibril subunit protein were digested with trypsin and the resulting peptides were separated by high performance liquid chromatography. Comparison with normal prealbumin peptides showed that an amino acid substitution of a methionine for a valine had occurred at position 30. In the plasma prealbumin, the abnormal residue accounted for 1/3rd of the material while in the amyloid fibrils it accounted for 2/3rds. From this sequence information and the known three-dimensional structure of the prealbumin molecule, a mechanism for the amyloid formation is proposed. It involves formation of the amyloid fibrils by addition of prealbumin dimers or tetramers to the aggregate. Each dimer must contain at least one variant peptide chain while the tetramer must contain at least two abnormal chains. Either of these models can account for the observed amount of normal prealbumin in amyloid fibrils. No proteolytic processing of this molecule is required because the entire undegraded prealbumin molecule is found in the fibrils.
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PMID:Primary structure of an amyloid prealbumin and its plasma precursor in a heredofamilial polyneuropathy of Swedish origin. 658 72

Amyloid fibril protein in patients with familial amyloidotic polyneuropathy is known to be chemically related to transthyretin (TTR), the plasma protein that is usually referred to as prealbumin. A genetically abnormal TTR may be involved in this disease. Studies were conducted on amyloid fibril protein (AFp) isolated from tissues of two Portuguese patients who died with familial amyloidosis, and on TTR isolated from sera of patients with this disease. AFp, purified by affinity chromatography on retinol-binding protein linked to Sepharose, resembled plasma TTR in forming a stable tetrameric structure, and in its binding affinities for both thyroxine and retinol-binding protein. The structural studies included: (a) comparative peptide mappings by reverse-phase high performance liquid chromatography (HPLC) after trypsin digestion; (b) cyanogen bromide cleavage studies; and (c) amino acid microsequence analysis of selected tryptic and CNBr peptides. On the basis of the known amino acid sequence of TTR, comparative tryptic peptide maps showed the presence of a single aberrant tryptic peptide (peptide 4, residues 22-34) in AFp as compared with TTR. This aberrant peptide contained a methionine residue, not present in normal tryptic peptide 4. CNBr cleavage of AFp produced two extra peptide fragments, which were demonstrated, respectively, by HPLC analysis and by sodium dodecyl sulfate-gel electrophoresis. Sequence analyses indicated the presence of a methionine-for-valine substitution at position 30 in AFp as compared with TTR. Thus, the purified amyloid fibril protein comprised a TTR variant with a methionine-forvaline substitution at position 30. A single nucleotide change in a possible codon for valine 30 could explain the substitution. The variant TTR was also present in the TTR isolated from the pooled sera of amyloidoses patients, together with larger (four- to six-fold) amounts of the normal TTR. Thus, in these patients, the variant TTR was circulating in plasma, along with larger amounts of normal TTR. We suggest that the variant TTR represents the specific biochemical cause of the disease, and that this abnormal form of TTR selectively deposits in tissues as the amyloid characteristic of the disease.
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PMID:Amyloid fibril protein in familial amyloidotic polyneuropathy, Portuguese type. Definition of molecular abnormality in transthyretin (prealbumin). 673 44

The plasma protein transthyretin (TTR) has the potential to form amyloid under certain conditions. More than 50 different point mutations have been associated with amyloid formation that occurs only in adults. It is not known what structural changes are introduced into the structure of this otherwise stable molecule that results in its aggregation into insoluble amyloid fibrils. On the basis of calculations of the frequency of known mutations over the polypeptide, we have constructed two mutants in the D-strand of the polypeptide. These molecules, containing either a deletion or a substitution at amino acid positions 53-55, were unstable and spontaneously formed aggregates upon storage in TBS (pH 7.6). The precipitates were shown to be amyloid by staining with thioflavin T and Congo Red. Their ultrastructure was very similar to that of amyloid fibrils deposited in the vitreous body of patients with familial amyloidotic polyneuropathy type 1 with an amino acid replacement in position 30 (TTRmet30). Like amyloid isolated from the vitreous body of the eye, the amyloid precipitates generated from the TTR mutants exposed a trypsin cleavage site between amino acid residues 48 and 49, while plasma TTRmet30 isolated from amyloidosis patients as well as wild-type TTR only showed minor trypsin sensitivity. Our data indicate that the mutants we have constructed are similar to amyloid precursors or may share structural properties with intermediates on a pathway leading to amyloid deposits of plasma TTR.
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PMID:Characterization of two highly amyloidogenic mutants of transthyretin. 915 16

Oxidative stress is increased in the retina in diabetes, and it is considered to play an important role in the development of retinopathy. alpha-Lipoic acid, a thiol antioxidant, has been shown to have beneficial effects on polyneuropathy and on the parameters of oxidative stress in various tissues, including nerve, kidney, and retina. The purpose of this study was to examine the effect of alpha-lipoic acid on retinal capillary cell apoptosis and the development of pathology in diabetes. Retina was used from streptozotocin-induced diabetic rats receiving diets supplemented with or without alpha-lipoic acid (400 mg/kg) for 11 months of diabetes. Capillary cell apoptosis (by terminal transferase-mediated dUTP nick-end labeling) and formation of acellular capillaries were investigated in the trypsin-digested retinal microvessels. The effect of alpha-lipoic acid administration on retinal 8-hydroxy-2'deoxyguanosine (8-OHdG) and nitrotyrosine levels was determined by enzyme-linked immunosorbent assay. alpha-Lipoic acid administration for the entire duration of diabetes inhibited capillary cell apoptosis and the number of acellular capillaries in the retina, despite similar severity of hyperglycemia in the two diabetic groups (with and without alpha-lipoic acid). Retinal 8-OHdG and nitrotyrosine levels were increased by over twofold and 70%, respectively, in diabetes, and alpha-lipoic acid administration inhibited these increases. Our results demonstrate that the long-term administration of alpha-lipoic acid has beneficial effects on the development of diabetic retinopathy via inhibition of accumulation of oxidatively modified DNA and nitrotyrosine in the retina. alpha-Lipoic acid supplementation represents an achievable adjunct therapy to help prevent vision loss in diabetic patients.
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PMID:Effect of long-term administration of alpha-lipoic acid on retinal capillary cell death and the development of retinopathy in diabetic rats. 1556 55