Phosphates and Phosphonates of Biochemical Interest

The structure and function of phosphoproteins has provoked much interest in the past year. The application of n.m.r. to the study of protein structure and function has been reviewed while the stereochemistry of enzymic phosphoryl transfer and the enzymology of kinases have been described in recent volumes of Methods in Enzymology. The identification of the sites of phosphorylation on phosphoproteins is an important prerequisite in attempting the elucidation of the functions of these compounds and methods have been described for the detection of 0-phosphoserine and 0-phosphotyrosine residues in proteins. The enzymic phosphorylation and dephosphorylation of tyrosine residues in proteins has been investigated, and a simple synthesis of O-phospho-L-tyrosine from the amino acid and a phosphoric oxide/orthophosphoric acid mixture has been described.  

There has been a continued interest in the chemistry and biochemistry of coenzymes, particularly phosphoenolpyruvate, and a book devoted to pyridine nucleotide coenzymes has been published as a tribute to Professor N. O. Kaplan s work on these compounds. Among new techniques which have been applied recently to biologically interesting compounds is fast atom bombardment mass spectrometry, which has been used in the structural elucidation of underivatized phospholipids.  

Reagents i, Me3SiBr/(4-dimethylamino)pyridine ii, Br2/CHaCl2 iii, (MeO)aPOSiMes iv, MesSiBr v, NaOEt/HjO 

Nicotinamide l,iV -ethenoadenine dinucleotide, prepared from NAD+ and chloroacetaldehyde, has been converted into 3-aminopyridine l,A -etheno-adenine dinucleotide (4) by a pyridine base exchange reaction which was catalysed by the venom of Bungarus fasciatus. Yeast alcohol dehydrogenase was 

A number of FAD analogues containing modifications in the isoalloxazine moiety have been prepared by incubation of the riboflavin analogues with the flavokinase/FAD synthetase system of Brevibacterium ammoniagenes. All 

Mitochondrial oxidative phosphorylation is the process by which ATP is synthesized in mitochondria during the passage of electrons along a chain of carriers. Chemical and chemiosmotic theories for this process have been propounded by their respective adherents, and mechanisms in bioenergetics have been reviewed, but experimental evidence to support these theories has been difficult to obtain with living systems. However, this year, reduced lipoic acid and unsaturated fatty acids have been shown to function as cofactors in the energy-linked synthesis of ATP in mitochondria, and this observation has prompted much activity in this field which will be discussed more fully in Section 6 of this Chapter. 

Another development worthy of comment is the number of P n.ra.r. studies on living tissue and cells that have been published during the past year. Resonances due to ATP, iV -phosphorocreatinine, and other compounds (such as glycerol 3-phos-phorylcholine) have been observed with muscle preparations. - With considerable experimental ingenuity, both heart tissue and perfused, beating rat hearts have 

Racker, A New Look at Mechanisms in Bioenergetics , Academic Press, New York, 1976. D. E. Griffiths, Biochem. /., 1976, 160, 809. 

Magnetic resonance techniques have again been popular for studying enzymes which are involved in phosphate hydrolysis and transfer. 31P or 19F N.m.r.1-2 and spinlabelling3 have all been used to study the interaction of substrates with these enzymes, while affinity labelling4 5 6 7 is another technique which has been used to obtain information about the sequence and conformation of amino-acid chains at the active sites of enzymes. Recently, these experimental methods have been applied to the study of cell membranes,6-7 and these are mentioned in a new series of books concerned with enzymes in biological membranes.8 A new journal, Trends in Biochemical Sciences, which contains concise, up-to-date reviews on these and other topics is published by Elsevier on behalf of the International Union of Biochemistry. 

8 The Enzymes of Biological Membranes , ed. A. Martonosi, Plenum Press, New York, 1976, Vols. 1 and 2. 

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