Open AccessCharacterization of two d ‐glyceraldehyde‐3‐phosphate dehydrogenases from the extremely thermophilic archaebacterium Thermoproteus tenax
Author(s) -
HENSEL Reinhard,
LAUMANN Silvia,
LANG Jutta,
HEUMANN Herrmann,
LOTTSPEICH Friedrich
Publication year - 1987
Publication title -
european journal of biochemistry
Language(s) - English
Resource type - Journals
eISSN - 1432-1033
pISSN - 0014-2956
DOI - 10.1111/j.1432-1033.1987.tb13703.x
Subject(s) - nad+ kinase , enzyme , biochemistry , thermophile , glyceraldehyde 3 phosphate dehydrogenase , thermostability , biology , chemistry , dehydrogenase
Thermoproteus tenax possesses two different glyceraldehyde‐3‐phosphate dehydrogenases, one specific for NADP + and the other for NAD + . NADP(H) inhibits the NAD + ‐specific enzyme competetively with respect to NAD + whereas NAD(H) virtually does not interact with the NADP + ‐specific enzyme. Both enzymes represent homomeric tetramers with subunit molecular masses of 39 kDa (NADP + ‐specific enzyme) and 49 kDa (NAD + ‐specific enzyme), respectively. The NADP + ‐specific enzyme shows significant homology to the known glyceraldehyde‐3‐phosphate dehydrogenases from eubacteria and eukaryotes as indicated by partial sequencing. The enzymes are thermostable, the NADP + ‐specific enzyme with a half‐life of 35 min at 100°C, the NAD + ‐specific enzyme with a half‐line of ≥20min at 100°C, depending on the protein concentration. Both enzymes show conformational and functional changes at 60 – 70°C.