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

UDP-galactose 4-epimerases from the yeast Kluyvero-myces fragilis and Escherichia coli are both homodimers but the molecular mass of the former (75 kDa/subunit) is nearly double that of the latter (39 kDa/subunit). Protein databank sequence homology revealed the possibility of mutarotase activity in the excess mass of the yeast enzyme. This was confirmed by three independent assay protocols. With the help of specific inhibitors and chemical modification reagents, the catalytic sites of epimerase and mutarotase were shown to be distinct and independent. Partial proteolysis with trypsin in the presence of specific inhibitors, 5'-UMP for epimerase and galactose for mutarotase, protected the respective activities. Similar digestion with double inhibitors cleaved the molecule into two fragments of 45 and 30 kDa. After separation by size-exclusion HPLC, they manifested exclusively epimerase and mutarotase activities, respectively. Epimerases from Kluyveromyces lactis var lactis, Pachysolen tannophilus and Schizosaccharomyces pombi also showed associated mutarotase activity distinct from the constitutively formed mutarotase activity. Thus, the bifunctionality of homodimeric yeast epimerases of 65-75 kDa/subunit appears to be universal. In addition to the inducible bifunctional epimerase/mutarotase, K. fragilis contained a smaller constitutive monomeric mutarotase of approximately 35 kDa.
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PMID:UDP-galactose 4-epimerase from Kluyveromyces fragilis. Evidence for independent mutarotation site. 1468 19

The long-term goal of our study is to identify chronic obstructive pulmonary disease (COPD)-related bronchoalveolar lavage fluid (BALF) nitroproteins to clarify COPD pathological mechanisms and to discover biomarkers of COPD. The goal of the present study was to detect the presence of, and potential roles of, nitroproteins in, human ex-smoker (without COPD) BALF samples. Nitroproteins were immunoprecipitated from two separate BALF samples, and digested with trypsin; and tryptic peptides were analyzed with matrix-assisted laser desorption/ionization (MALDI)-tandem mass spectrometry (MS/MS). Each MS/MS spectrum was composed of accumulated scans (n = 50-100). The MS/MS data were searched with BioWorks 2.0 TuboSequest in the SwissProt database to generate the amino acid sequence, which was evaluated manually. Eleven nitrotyrosine sites were identified in eight proteins, including progestin and adipoQ receptor family member III, zinc finger protein 432, proteasome subunit alpha type 2, NADH-ubiquinone oxidoreductase B14, slit homolog 1 protein, lysozyme, aldose 1-epimerase, and PTS system lactose-specific EIICB component. Each nitrotyrosine site was located within a specific protein domain and motif. Those identified nitrated proteins could be involved in multiple functional metabolic systems, including transcriptional regulation, mitochondrial complex, immune system, and energy metabolism.
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PMID:Nitroproteins Identified in Human Ex-smoker Bronchoalveolar Lavage Fluid. 2239 69