Characterization of a novel class of glyoxylate reductase belonging to the β-hydroxyacid dehydrogenase family in Acetobacter aceti

A novel reductase displaying high specificity for glyoxylate and NADPH was purified 3343-fold from spinach leaves. The enzyme was found to be an oligomer of about 125 kDa, composed of four equal subunits of 33 kDa each. A Km for glyoxylate was about 14-fold lower with NADPH than with NADH (0.085 and 1.10 mM respectively), but the maximal activity, 210 mumol/min per mg of protein, was similar with either cofactor. Km values for NADPH and NADH were 3 and 150 microM respectively. Optimal rates with either NADPH or NADH were found in the pH range 6.5-7.4. The enzyme also showed some reactivity towards hydroxypyruvate with rates less than 2% of those observed for glyoxylate. Results of immunological studies, using antibodies prepared against either glyoxylate reductase or spinach peroxisomal hydroxypyruvate reductase, suggested substantial differences in molecular structure of the two proteins. The high rates of NADPH(NADH)-glyoxylate reductase in crude leaf extracts of spinach, wheat and soya bean (30-45 mumol/h per mg of chlorophyll) and its strong affinity for glyoxylate suggest that the enzyme may be an important side component of photorespiration in vivo. In leaves of nitrogen-fixing legumes, this reductase may also be involved in ureide breakdown, utilizing the glyoxylate produced during allantoate metabolism.

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Isolation and characterization of Acetobacter aceti from rotten papaya

Journal of the Bangladesh Agricultural University ◽

10.3329/jbau.v13i2.28802 ◽

2016 ◽

Vol 13 (2) ◽

pp. 299-306 ◽

Cited By ~ 2

Author(s):

J Kowser ◽

MG Aziz ◽

MB Uddin

Keyword(s):

Cell Mass ◽

Single Pair ◽

Acetobacter Aceti ◽

Biochemical Tests ◽

Isolation And Characterization ◽

The Media ◽

Durham Tube ◽

Successive Subculture ◽

Dry Cell

The present study was concerned with the isolation and characterization of Acetobacter aceti from rotten papaya for vinegar production. The samples were inoculated in sterilized GYC standard media and then incubated at 30°C for 48 hours. Successive subculture was performed to screen out the strains. In Grams staining, the morphology of the isolated bacteria exhibited pink, small rod shaped single, pair and chain in arrangement, in the hanging drops technique, all the isolates revealed motile. Biochemical tests were performed by fermentation of five basic sugars by producing both acid and gas bubbles in Durham tube. All of the isolates were Indole, Voges-Proskauer (VP) and Oxidase negative, Methyl Red (MR) and Catalase positive. The growth rate of isolated strain was optimized by weighing dry cell and turbidity at 600 nm at different concentrations of dextrose (1%, 5% and 10%). Ten (10) percent dextrose solution showed rapid growth and higher cell mass than 5% and 1% solution respectively. Acidity of the media gradually increased from 0.102% to 2.18% from day 0 to day 7 and pH of the media decreased from 6.8 to 5.5 during the period. This protocol was successful for enriching Acetobacter aceti, which was essential for vinegar production.J. Bangladesh Agril. Univ. 13(2): 299-306, December 2015

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