Carbonic anhydrase activity in isolated chloroplasts of chlamydomonas reinhardtii
- Indiana Univ., Bloomington (USA)
- Carnegie Institute, Stanford, CA (USA)
- Louisiana State Univ., Baton Rouge (USA)
In a new assay of carbonic anhydrase, NaH{sup 14}CO{sub 3} solution at the bottom of a sealed vessel releases {sup 14}CO{sub 3} which diffuses to the top of the vessel to be assimilated by actively photosynthesizing Chlamydomonas cells. The assay is initiated by illuminating cells and stopped by turning the light off and killing the cells with acid. Enzyme activity was estimated from acid stable radioactivity above the uncatalyzed background level. With bovine carbonic anhydrase, 1.5 Wilbur Anderson Unit (WAU) can be consistantly measured at 5-6 fold above background. Sonicated whole cells of air adapted wild type (+)gave 741.1 {plus minus} 12.4 WAU/mg chl. Intact washed cells of mixotrophically grown wall-less mutant CWD(-) and a high CO2 requiring wall-less double mutant CIA-3/CW15 (-) gave 7.1 {plus minus} 1.9 and 2.8 {plus minus} 7.8 WAU/mg chl respectively. Chloroplasts isolated from CWD and CIA-3/CW15 and subsequently disrupted gave 64.0 {plus minus} 14.7 and 2.8 {plus minus} 3.2 WAU/mg chl respectively. Chloroplast sonicate from another wall-less mutant CW15(-) gave activity comparable to CWD. Thus on a chlorophyll basis, enzyme activity in chloroplasts from mixotrophically grown cells is about 1/10th of the level found in air adapted wild type cells. CIA-3 seems to lack this activity.
- OSTI ID:
- 7191622
- Journal Information:
- Plant Physiology, Supplement; (USA), Vol. 89:4; ISSN 0079-2241
- Country of Publication:
- United States
- Language:
- English
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Related Subjects
CHLAMYDOMONAS
ENZYME ACTIVITY
CARBON 14 COMPOUNDS
CARBON DIOXIDE
CARBONIC ANHYDRASE
MUTANTS
TRACER TECHNIQUES
ALGAE
CARBON COMPOUNDS
CARBON OXIDES
CARBON-OXYGEN LYASES
CHALCOGENIDES
CHLOROPHYCOTA
ENZYMES
HYDRO-LYASES
ISOTOPE APPLICATIONS
LABELLED COMPOUNDS
LYASES
MICROORGANISMS
OXIDES
OXYGEN COMPOUNDS
PLANTS
UNICELLULAR ALGAE
550201* - Biochemistry- Tracer Techniques