Biochemical significance

Standards are available which cater for the performance of over 400 chemical analyses these include the determination of several metals and of a number of organic substances, including many of biochemical significance. 

V. Solinas, S. Deiana, C. Gessa, C. Pistidda, and R. Rausa, Reduction of the Felll-desferrioxamine-B complexes by caffeic acid a reduction mechanism of biochemical significance. Soil. Biol. Biochem. 275 649 (1996). 

However, the biochemical significance of the latter studies is challenged by the fact that the transformation of transient purine and pyrimidine radicals into diamagnetic decomposition products is oxygen-independent in the solid state. Therefore, it is necessary to study the chemistry of one-electron nucleobase intermediates in aerated aqueous solutions in order to investigate the role of oxygen in the course of reactions that give rise to oxidation products within DNA and model compounds. In this respect, type I photo-... 

It is not an exaggeration to say that electrospray has introduced a new era, not only for the analytical mass spectroscopist, but also for the more physically oriented researcher interested in physical measurements involving the above ions, which are of such great importance in condensed-phase ion chemistry. In particular, gas-phase ions produced by electrospray allow, for the first time, thermochemical measurements involving ions of biochemical significance such as protonated peptides, deprotonated nucleotides, and metal ion complexes with peptides and proteins. It is to be expected that such data will be of importance in the development of theoretical modeling of the state of these systems in the condensed phase.34,35... 

It is now well known that pantothenic acid is a part of coenzyme A, a substance of unusual biochemical significance in that it is intimately concerned with the utilization of carbohydrates, and both the utilization and synthesis of fats, sterols, steriod hormones, etc. A partial failure of any of the processes in which it is concerned may not produce a specific lesion, but may nevertheless be a serious detriment to the individual experiencing it. 

The nucleotide cyclic AMP (3, 5 -cyclic adenosine monophosphate, cAMP) is a cyclic phosphate ester of particular biochemical significance. It is formed from the triester ATP by the action of the enzyme adenylate cyclase, via nucleophilic attack of the ribose 3 -hydroxyl onto the nearest P=0 group, displacing diphosphate as leaving group. It is subsequently inactivated by hydrolysis to 5 -AMP through the action of a phosphodiesterase enzyme. 

The true biochemical significance of this deamination, and the function of the secondary metabolic pathway originating from L-phenylalanine (6-... 

Biochemical Significance of the Phenylalanine-Cinnamate Pathway in Plants and Fungii... 

A biochemically significant Claisen rearrangement is the transformation of choris-mate into prephenate [232] via a chair transition state. Although it is impossible to settle the question of the direction of electron flow during the reorganization, that shown by the arrows in the formula should be preferred when the influence of the various substituents is considered. 

Muzzarelli, R. (1994). In vivo biochemical significance of chitin-based medical items. In "Polymeric Biomaterials", (S. Dumitriu, Ed.), pp. 179-197. Marcel Dekker, New York. 

In its compounds nickel usually has the +2 oxidation state but the +3 and +4 states occur rarely in complexes. Tire Ni2+ ion contains eight 3d electrons, a configuration that favors square-planar coordination of four ligands. However, the ion is also able to form a complex with six ligands and an octahedral geometry. It has been suggested that this "ambivalence" may be of biochemical significance. 

A few radioisotopes of biochemical significance are y emitters. Emission of a y ray (a photon of electromagnetic radiation) is often a secondary process occurring after the initial decay by /3 emission. The disintegration of the isotope 131I is an example of this multistep process. 

A thorough understanding of the biochemical significance of ligand binding to macromolecules comes only from a quantitative analysis of the strength of binding. (In biochemistry, a small molecule that binds to... 

The presence of many chiral centers in compounds of biochemical significance or natural-product interest has led to the use of stereoparents. These are parent structures having trivial names that imply (without explicitly expressing) a particular steric configuration. Common examples are the names of simple sugars, exemplified by glucose. 

Lorimer, G. H., The carboxylation and oxygenation of ribulose-1,5-bisphosphate The primary events in photosynthesis and photorespiration. Ann. Rev. Plant Physiol. 32 349, 1981. Mechanisms and biochemical significance of the carboxylase and oxygenase reactions. 

Schiff base formation can have a considerable effect on both the position and degree of activation of the coordinated amino acid. The Schiff bases derived from amino acids and pyridoxal have attracted considerable attention due to the biochemical significance of vitamin B6 and the realization that many of the enzymic reactions involving B6 could be brought about in the absence of enzyme by using pyridoxal and various metal ions.444,445,461 4 2,342... 

Lenaz, G., Sechi, A. M., Masotti, L., and Parenti-Castelli, G. Lipid-protein interactions in mitochondria. II. On the nature and biochemical significance of the interaction between phospholipids and lipid-depleted mitochondria. Arch. Biochem. Biophys. 141, 89-97 (1970). 

Conventional electron impact or chemical ionization mass spectrometry requires that volatilization precede ionization and this is clearly a limiting factor in the analysis of many biochemically significant compounds. A newer ionization technique, field desorption (FD) (1, 2 ) removes this requirement and makes it possible to obtain mass spectrometric information on thermally unstable or non-volatile organic compounds such as glycoconjugates and salts. This development is particularly significant for those concerned with the analysis of glycolipids and we have therefore explored the suitability of field desorption mass spectrometry (FDMS) for this class of compounds. We have evaluated experimental procedures in order to enhance the efficiency of the ionization process and to maximize the information content of spectra obtained by this technique. 

Heterocycles are ubiquitous in nature, with manifold industrial applications, and in all aspects of our life. In nature they occur in multiple forms, and they possess enormous biochemical significance - "the molecules of life." The applications of heterocycles that are drawn from chemistry, biology, medicine, agriculture, and industry are legion. 

It has been proposed that a low molecular weight phosphoprotein of phosvitin nature (47) which binds iron with high affinity may be involved in the cytosolic transport of iron in liver cells (48, 49), but no energized uptake of iron has been demonstrated such as in isolated rat liver mitochondria using a Fe(III)-phosvitin from avian egg yolk (mol wt 40,000) as the substrate (50). The biochemical significance of the cytosolic iron binding phosphoprotein is therefore still uncertain. 

Biochemical Significance of the Iron Transporting System of Mitochondria... 

---