Isolation of β-Amylase Producing Microorganisms

l,3-Diphenyl-2-propen-l-one (chalcone) was selectively hydrogenated at the carbon-carbon double bond on incubation with Corynebacterium equi IFO 3730, to give the corresponding saturated ketone, 1,3-diphenyl-l-propanone. Practically no alcoholic compounds were detected in the reaction mixture. This highly selective hydrogenation reaction was also successful with substrates having substituents on aromatic rings. On the other hand, two hydrogen atoms on the olefinic carbons were essential, because substitution of either one of the hydrogens by a methyl group completely inhibited the reaction.     

Types of Amylases in Rice Grains

The subunit structure of phenoloxidase from the larvae of housefly, Musca domestica vicina Maquart, was investigated by urea treatment, SDS-polyacrylamide gel electrophoresis and electron microscopy. Phenoloxidase was dissociated into a single type of subunit (MW 6.5 × 10⁴) by 5 m urea treatment. A similar subunit (MW 6.1 × 10⁴) was also detected by SDS-polyacrylamide gel electrophoresis. Furthermore, four additional protein bands with molecular weights of 4.8 × 10⁴, 3.5 × 10⁴, 2.4 × 10⁴ and 1.2 × 10⁴ were detected by SDS-polyacrylamide gel electrophoresis by extensive incubation of phenoloxidase with SDS. A cylindrical molecular structure was deduced from the electron microscopic analysis. The outside and inside diameter and the height of phenoloxidase molecule were evaluated to be 100, 50 and 70 Å, respectively.     

Studies on Barley and Malt Amylases

From the 2 m urea extract of ground barley two zymogen β-amylase (Z-β-A) fractions (Fractions A and B) and one active β-amylase (A-β-A) fraction (Fraction C) were isolated by Sephadex G-75 gel filtration and purified by DEAE-Sephadex A-50 column chromatography. The molecular weights of Fractions A, B and C were estimated to be approximately 280,000, 160,000 and 56,000, respectively.

Both the Z-β-A fractions which were ultracentrifugally and electrophoretically homogeneous were found to be accompanied by a small amount of saccharogenic activities. From the estimation of Km values for these saccharogenic activities and the behavior in their activation with 2-mercaptoethanol and papain, it seems reasonable to conclude that Fraction A is a heteropolymer type of Z-β-A composed of both A-β-A and barley reserve proteins; that Fraction B is a homopolymer type of Z-β-A composed of A-β-A alone; and that two different activation mechanisms, proteolytic activation and disulfide bond cleaving activation, are necessary for full activation of Z-β-A in barley.