Mukund S, Adams M W
Department of Biochemistry and Molecular Biology, University of Georgia, Athens 30602, USA.
J Biol Chem. 1995 Apr 14;270(15):8389-92. doi: 10.1074/jbc.270.15.8389.
The archaeon Pyrococcus furiosus grows optimally at 100 degrees C by the fermentation of carbohydrates to yield acetate, CO2, and H2. Cell-free extracts contain very low activity of the glycolytic enzyme, glyceraldehyde-3-phosphate dehydrogenase, but extremely high activity of glyceraldehyde-3-phosphate ferredoxin oxidoreductase (GAPOR). GAPOR was purified under strictly anaerobic conditions. It is a monomeric, O2-sensitive protein of M(r) approximately 63,000 which contains pterin and approximately 1 tungsten and 6 iron atoms per molecule. The enzyme oxidized glyceraldehyde-3-phosphate (Km 28 microM) to 3-phosphoglycerate and reduced P. furiosus ferredoxin (Km 6 microM), but it did not oxidize formaldehyde, acetaldehyde, glyceraldehyde, benzaldehyde, glucose, glucose 6-phosphate, or glyoxylate, nor did it use NAD(P) as an electron acceptor. It is proposed that GAPOR has a glycolytic role and functions in place of glyceraldehyde-3-phosphate dehydrogenase and possibly phosphoglycerate kinase.
嗜热栖热菌在100摄氏度时通过碳水化合物发酵产生乙酸盐、二氧化碳和氢气，生长最为适宜。无细胞提取物中糖酵解酶甘油醛-3-磷酸脱氢酶的活性非常低，但甘油醛-3-磷酸铁氧化还原酶（GAPOR）的活性极高。GAPOR是在严格厌氧条件下纯化得到的。它是一种单体蛋白，对氧气敏感，分子量约为63,000，每个分子含有蝶呤、约1个钨原子和6个铁原子。该酶将甘油醛-3-磷酸（Km为28微摩尔）氧化为3-磷酸甘油酸，并还原嗜热栖热菌铁氧化还原蛋白（Km为6微摩尔），但它不氧化甲醛、乙醛、甘油醛、苯甲醛、葡萄糖、6-磷酸葡萄糖或乙醛酸，也不以NAD(P)作为电子受体。有人提出，GAPOR具有糖酵解作用，可替代甘油醛-3-磷酸脱氢酶，可能还替代磷酸甘油酸激酶发挥功能。
