Gene/Protein Disease Symptom Drug Enzyme Compound
Pivot Concepts:   Target Concepts:
Query: UMLS:C0027960 (mole)
 21,279 document(s) hit in 31,850,051 MEDLINE articles (0.00 seconds)

A method has been developed for the purification of alliinase from garlic bulbs. High purity preparations of the enzyme were obtained with specific activity increased 67-fold over that of the homogenate. The preparations were homogeneous on electrophoresis in polyacril gel. Total activity yield was 25%. The native enzyme has a molecular weight of 130.000 and consists of two subunits. Approximately 6 moles of firmly bound pyridoxal phosphate are determined per 1 mole of the purest enzyme (4 equivalents are apparently bound non-specifically outside the active sites). The isoelectric point (pI) of alliinase in 6.2. The enzyme's absorption and circular dichroism spectra have one maximum at 430 nm, in the characteristic range of many pyridoxal-P-containing enzymes. The Km value for the natural substrate, alliin, is 5 . 10(-4) M.
 ...
PMID:[Alliinase: purification and chief physico-chemical properties]. 71 59

Garlic and onion alliin lyases, although from closely related species, have many differences. The two enzymes differ in their K(m) values, pH optima, and isoelectric points. There is a major difference in their molecular weight and subunit structure. The garlic holoenzyme has a molecular weight of 85,000 and consists of two subunits of molecular weight 42,000. The onion enzyme has a holoenzyme molecular weight of 200,000 composed of four subunits of molecular weight 50,000. The onion enzyme is much more difficult to dissociate into its subunits which suggests differences in subunit interaction between the two enzymes. The dimeric stucture of the garlic and the tetrameric structure of the onion enzyme is consistent with a coenzyme content (pyridoxal-5'-phosphate) equivalent to one mole per subunit. The two enzymes vary vastly in their spectra, the onion enzyme having a lower pyridoxal-5'-phosphate absorbance at 430 nanomoles and an inability to react with l-cysteine. Both enzymes are glycoproteins and bind to concanavalin A-Sepharose columns. The onion alliin lyase binds more tightly than the garlic enzyme. The amino acid content of both enzymes is similar as is the carbohydrate content. However, upon hydrolysis the onion lyase does yield more mannose units than the garlic enzyme which is consistent with the former's stronger affinity for concanavalin A.
 ...
PMID:The C-S Lyases of Higher Plants : Direct Comparison of the Physical Properties of Homogeneous Alliin Lyase of Garlic (Allium sativum) and Onion (Allium cepa). 1666 7