title: Subunit constitution of carbonic anhydrase from Chlamydomonas reinhardtii.
abstract: Carbonic anhydrase purified from the cell surface of Chlamydomonas reinhardtii was inactivated by treatment with dithiothreitol. This treatment caused dissociation of the holoenzyme into 35-kDa (A) and 4-kDa (B) subunits as revealed by SDS/PAGE. The 35-kDa subunit was further separated into two components A1 (35 kDa) and A2 (36.5 kDa) by SDS/PAGE using a gradient gel. These two components have the same amino acid sequence up to at least the 10th amino acid from the N-terminus. The molecular masses were estimated at 76 kDa and 35 kDa for the holoenzyme and the large subunit, respectively, and the molar ratio of the former to the latter at 1:2, by using the techniques of low-angle laser light-scattering photometry and precision differential refractometry combined with gel-filtration HPLC. The molar ratio of the 35-kDa/4-kDa subunits was estimated at 1:1 the gel-filtration HPLC monitored with precision differential refractometry. Atomic-absorption spectrophotometry revealed that the holoenzyme contains two atoms of zinc. These results suggest that the holoenzyme is a heterotetramer composed of two large subunits (A1 and A2) and two small subunits (B).
authors.affiliation: Institute of Applied Microbiology, University of Tokyo, Japan.
authors.forename: T
authors.initials: T
authors.lastname: Kamo
authors.forename: K
authors.initials: K
authors.lastname: Shimogawara
authors.forename: H
authors.initials: H
authors.lastname: Fukuzawa
authors.forename: S
authors.initials: S
authors.lastname: Muto
authors.forename: S
authors.initials: S
authors.lastname: Miyachi
mesh_terms: D000595:Amino Acid Sequence; D000818:Animals; D002256:Carbonic Anhydrases / Q000235:genetics* / Q000302:isolation & purification; D002462:Cell Membrane / Q000201:enzymology; D002696:Chlamydomonas / Q000201:enzymology*; D002851:Chromatography, High Pressure Liquid; D004591:Electrophoresis, Polyacrylamide Gel; D006801:Humans; D046911:Macromolecular Substances; D008969:Molecular Sequence Data; D008970:Molecular Weight; D010446:Peptide Fragments / Q000302:isolation & purification; D010449:Peptide Mapping; D012689:Sequence Homology, Nucleic Acid
chemical_list: D046911:Macromolecular Substances; D010446:Peptide Fragments; D002256:Carbonic Anhydrases