Glucose glycolysis (10 successive reactions) anaerobic anaerobic conditions 2 Pyruvate conditions aerobic 2 Ethanol +2CO2 conditions 2 Lactate 2C02 Fermentation to alcohol Fermentation to in yeast lactate in vigorously 2 Acetyl-CoA contracting muscle, erythrocytes,some other cells,and in citric acid some microorganisms cycle 4CO2+4H2O Animal,plant,and many microbial cells under aerobic conditions
CH2OH CH20P0号 0 -0 H H H H H Mg·ATP+ hexokinase 0H1 H Mg·ADP+ OH H HO OH HO OH H OH H OH Glucose Glucose 6-phosphate 葡萄糖(glucose G) -1ATP 6-磷酸葡萄糖(glucose-6-phophate,.G一6一P) 己糖激酶hexokinase,HK。 葡萄糖激酶(glucokinase,.GK)
-1ATP 葡萄糖(glucose G) 6-磷酸葡萄糖(glucose-6-phophate, G-6-P) 己糖激酶(hexokinase,HK)。 葡萄糖激酶(glucokinase,GK)
6一磷酸葡萄糖是HK的反馈抑制物,此酶是糖氧化 反应过程的限速酶(rate limiting enzyme)或称关键酶 (key enzyme)。它有同工酶I-V型,I、Ⅱ、Ⅲ型主 要存在于肝外组织,其对葡萄糖Km值为10-5~10M。 V型主要存在于肝脏,特称葡萄糖激酶 (g1 ucokinase,GK),对葡萄糖的Km值1~102M,正常血 糖浓度为5mmo1/L,当血糖浓度升高时,GK活性增加, 促进合成糖原,6一磷酸葡萄糖对此酶无抑制作用
6-磷酸葡萄糖是HK的反馈抑制物,此酶是糖氧化 反应过程的限速酶(rate limiting enzyme)或称关键酶 (key enzyme)。它有同工酶Ⅰ-Ⅳ型,Ⅰ、Ⅱ、Ⅲ型主 要存在于肝外组织,其对葡萄糖Km值为10-5~10-6M。 Ⅳ型主要存在于肝脏,特称葡萄糖激酶 (glucokinase,GK),对葡萄糖的Km值1~10-2M,正常血 糖浓度为5mmol/L,当血糖浓度升高时,GK活性增加, 促进合成糖原, 6-磷酸葡萄糖对此酶无抑制作用
O-P CH2 HO-CH2 5 ATP ADP H H 4g3 H H OH hexokinase OH HO OH HO OH 3 2 H OH H OH Glucose Glucose 6-phosphate △G°=-16.7kJ/mol
0 6 H2C-0-P-0 CH2OH 0 H H H H H HO OH H OH HO OH H OH H OH H OH Glucose Hexokinase Glucose 6-phosphate ATP ADP Reaction Coupling