Formation biogenic

Pyridoxal phosphate mainly serves as coenzyme in the amino acid metabolism and is covalently bound to its enzyme via a Schiff base. In the enzymatic reaction, the amino group of the substrate and the aldehyde group of PLP form a Schiff base, too. The subsequent reactions can take place at the a-, (3-, or y-carbon of the respective substrate. Common types of reactions are decarboxylations (formation of biogenic amines), transaminations (transfer of the amino nitrogen of one amino acid to the keto analog of another amino acid), and eliminations. 

Sillen, A. 1986 Biogenic and diagenetic Sr/Ca in Plio-Pleistocene fossils of the Omo Shungura formation. PaZeohioZogv 12 311-323. 

Denitrification involves the sequential formation of nitrite, nitric oxide, and nitrous oxide. Two aspects of nitric oxide have attracted attention (a) chemical oxidation of biogenic nitric oxide to Nq, in the context of increased ozone formation (Stohl et al. 1996) and (b) the physiological role in mammalian systems (Feldman et al. 1993 Stuehr et al. 2004), in parasitic infections (James 1995), and in the inhibition of bacterial respiration (Nagata et al. 1998). Nitric oxide may be produced microbiologically in widely different reactions such as... 

Major problems in oil and gas operations result from the biogenic formation of hydrogen sulfide (H2S) in the reservoir. The presence of H2S results in increased corrosion, iron sulfide formation, higher operating costs, and reduced revenue and constitutes a serious environmental and health hazard. 

E. S. Littmann and T. L. McLean. Chemical control of biogenic H2S in producing formations. In Proceedings Volume, pages 339-342. SPE Prod Oper Symp (Oklahoma City, OK, 3/8-3/10), 1987. 

Further capture of a-particles leads to the formation of oxygen and neon. 160 itself forms the basis for the synthesis of sulphur. The only biogenic element missing in Table 2.2 is phosphorus, which is an exception in that it is formed by a complex nuclear synthesis (Macia et al., 1997). In large stars, the reactions listed in the table take place in the following series, without stopping but over long periods of time. 

Lopez, P.J., Gautier, C., Livage, J. and Coradin, T. (2005) Mimicking biogenic silica nanostructures formation. Current Nanoscience, 1, 73—83. 

Biogenic structures Structures in fossils or rock formations that may have been formed by biological activity. 

The subject of metabolism of tetrahydroisoquinolines and related alkaloids in mammalian metabolic systems has recently been reviewed (205, 206). The formation of biogenic amine-derived alkaloids in mammals and their transformation by O-methylation reactions have been described. 

It is doubtful that formation and dissolution of any mineral in low temperature aqueous solutions has been more fully investigated than the magnesian caicite. This mineral is a preponderant carbonate phase, mostly of biogenic origin, in seawater. Fig. 8.8 gives some data on the solubilities of Mg-calcites as a function of MgC03 content. 

Table 3. Summary of Fe isotope fractionations during biogenic mineral formation.

The activity of decarboxylase can be an indirect measurement of the potential for biogenic amine formation. A study by Middlebrooks et al. (1988)... 

The most important factors contributing to the production of biogenic amines during postharvest handling are the duration of storage and the storage temperature. Both the post-mortem formation of amino acids and their rapid decarboxylation are temperature dependent. 

The effect of temperature on histamine formation has been the subject of many studies (Table 6.5). Different studies reported 100-fold variations in histamine concentrations in skipjack tuna allowed to spoil under similar conditions. Although the information in Table 6.5 contains substantial variation, it is obvious that longer storage times and higher temperatures seem to induce histamine production. Control of biogenic amine production by low temperatures (for example 0°C) is consistently observed. 

Biogenic amine formation in fish and fish products. 

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