微藻光合作用制氢——能源危机的最终出路?

微藻光合作用制氢是解决能源短缺问题的有效途径.本文介绍了微藻光合作用制氢的机理,包括蓝藻固氮酶和可逆氢酶产氢以及绿藻可逆氢酶产氢的机理.在分析光合制氢限制因素的基础上,指出筛选和构建高效放氢藻株是制氢的有效途径.然后介绍了“直接生物光解”、固氮酶放氢和“间接生物光解”等制氢方式.利用绿藻“间接生物光解”水制氢是一种最有发展潜力的制氢方式.本文最后展望了微藻光合制氢的前景.     

Differences in specificity and catalytic efficiency between allozymes of esterase-4 from Drosophila mojavensis

A more than 10-fold difference in the specificity and catalytic efficiency for 1-naphthyl esters was measured between two allozymes of esterase-4 from Drosophila mojavensis. This difference is mainly caused by a difference in the affinity for the 1-naphthyl esters. The amino acid compositions of the allozymes are not significantly different, which means that the difference in primary structure is small. Small differences in primary structure generally do not result in such a large increase in catalytic efficiency and such a large shift in substrate specificity as was found in the present study.