Cyanobacteria enzyme activity

Stoecker, D., Autio, R., Rintala, J. M., and Kuosa, H. (2005). Ecto-ceUular enzyme activity associated with filamentous cyanobacteria. Aquat. Microb. Ecol. 40, 151—161. 

Under aerobic environmental conditions nitrogen fixation by cyanobacteria is restricted to heterocystous species. In these organisms, nitrogenase is localized within heterocysts which provide for anaerobic conditions necessary to keep the oxygen-labile enzyme active. Nevertheless, nitrogenase activity has also been observed in non-heterocystous cyanobacteria (Stewart, Lex 1970 Rippka, Waterbury 1977). 

Two classes of aldolase enzymes are found in nature. Animal tissues produce a Class I aldolase, characterized by the formation of a covalent Schiff base intermediate between an active-site lysine and the carbonyl group of the substrate. Class I aldolases do not require a divalent metal ion (and thus are not inhibited by EDTA) but are inhibited by sodium borohydride, NaBH4, in the presence of substrate (see A Deeper Look, page 622). Class II aldolases are produced mainly in bacteria and fungi and are not inhibited by borohydride, but do contain an active-site metal (normally zinc, Zn ) and are inhibited by EDTA. Cyanobacteria and some other simple organisms possess both classes of aldolase. 

The decrease of peak numbers was observed, when the spectra of the same amounts of fresh (12 weeks old) and aged (9 months old) mortars were compared. This decrease might be caused by activity of ubiquitous microorganisms that live on the mortar surfaces in biofilms. Especially in mild climate conditions, algae and cyanobacteria [35] can appear here moulds (Aspergillus, Penicillium, Fusarium, Mucor) [36] and bacteria (Arthrobacter Bacillus, Micrococcus, Staphylococcus) [37,38] have been discovered as well. The microorganisms secrete various hydrolytic enzymes that can decompose the organic additives, namely proteins, and make their sample identification less sensitive... 

The importance of manganese for bacteria, such as that of Ni and to a lesser extent Co, as we saw in the last chapter, is considerable. Of course, as we will see shortly, it is also important in the tetranuclear Mn cluster that is involved in oxygen production in photosynthetic plants, algae and cyanobacteria, as well as in a number of mammalian enzymes such as arginase and mitochondrial superoxide dismutase. Most of manganese biochemistry can be explained on the one hand by its redox activity, and on the other by its analogy to Mg2+ (reviewed in Yocum and Pecoraro, 1999). 

In bacteria this enzyme is usually inhibited by AMP and ADP and activated by glycolytic intermediates such as fructose 1,6-P2, fructose 6-P, or pyruvate. In higher plants, green algae, and cyanobacteria the enzyme is usually activated by 3-phosphoglycerate, a product of photosynthetic C02 fixation, and is inhibited by inorganic phosphate (Pj).106 108. 

In plants a similar enzyme catalyzes formation of the first double bond in a fatty acyl group converting stearoyl-ACP into oleoyl-ACP in the chloroplasts.72 753/105 108 The soluble A9 stearoyl-ACP desaturase has a diiron-oxo active site (Fig. 16-20, B, C).i°9 no Electrons are donated from light-generated reduced ferredoxin (see Chapter 23). In addition to the A9 desaturase both plants and cyanobacteria usually desaturate C18 acids also at the A12 and A15 positions and C16 acids at the A7, A20, and A13 (co3) positions.iii ii2 Desaturation of oleate occurs primari-... 

---