Glyceraldehyde-3-phosphate dehydrogenase in the hyperthermophilic archaeon Sulfolobus solfataricus: characterization and significance in glucose metabolism.
Glyceraldehyde-3-phosphate dehydrogenase in the archaeon Sulfolobus solfataricus (SsGAPD) has been purified 232 fold with an overall recovery of about 25%. The enzyme is a homomeric tetramer with an M(r) of 41 kDa/subunit. It utilizes either NAD+ or NADP+ as coenzyme but its affinity for the latter is about 50 fold higher. SsGAPD activity is maximum at 87 degrees C. In the range 45-87 degrees C the Arrhenius plot is linear and the activation energy is 55 kJ/mol. The enzyme is thermostable, with a half-life of 45 min at 87 degrees C. The primary structure of SsGAPD shows 35% identity with that of other archaeal GAPDs. Its N-domain shows sequence motifs typical of the dinucleotide binding proteins while the catalytic C-terminal region contains a cysteine residue (C140), required for catalysis, that is conserved in all the archaeal, eukaryal and bacterial GAPDs. These remarks suggest that archaeal GAPDs show a convergent molecular evolution to the eukaryal and eubacterial enzymes in the catalytic region.
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Dipartimento di Biochemica e Biotecnologie Mediche, Università di Napoli Federico II, Italia.
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Masullo
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Ianniciello
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Arcari
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Bocchini
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D000595:Amino Acid Sequence; D005075:Biological Evolution; D004795:Enzyme Stability; D005947:Glucose / Q000378:metabolism*; D005987:Glyceraldehyde-3-Phosphate Dehydrogenases / Q000737:chemistry / Q000302:isolation & purification / Q000378:metabolism*; D007700:Kinetics; D008969:Molecular Sequence Data; D008970:Molecular Weight; D009243:NAD / Q000378:metabolism; D009249:NADP / Q000378:metabolism; D016415:Sequence Alignment; D016944:Sulfolobus / Q000737:chemistry / Q000201:enzymology*; D013696:Temperature
D009243:NAD; D009249:NADP; D005987:Glyceraldehyde-3-Phosphate Dehydrogenases; D005947:Glucose