SOME NEW KEYS TO COSMETIC CHEMISTRY--19$6 239 conditions. sa Denaturation was considered to involve extensive disturbance of weak bonds formed by the side chains, without alteration of many intra- chain bonds. 8• The conditions for the helix-to-random-coil transition in- volved in denaturation were more narrowly defined, and methods were devised for inducing the controlled degradation of nucleic acid necessary for study of its structure. 85 Ribonucleic acid 8ø and deoxyribonucleic acid" were synthesised, albeit by enzymatic methods which shed little light on the structure. A theory was advanced to explain elastic mechanisms in fibrous proteins on the basis of melting of their crystalline regions, 88 such melting possibly occurring as the result of an agent which combines more readily with the liquid protein, thus shifting the equilibrium.89 COLLAGEN AND ELASTIN Recent books bearing upon collagen include Fibrous Proteir•s arid Their Biological Significance, 9 o originating in the Society for Experimental Biology, and The Chemistry arid Reactivity of Collagen 9•. by K. H. Gustarson. Numer- ous investigators have contributed to the cracking of the tough problem of collagen structure, but a working model acceptable to all parties is still lacking. There seems to be general agreement92, 9• that collagen possesses a three-chain coiled-coil structure with right-handed major and left-handed minor helix, 9•,95 with individual chains ending at staggered positions. The chains are most probably of the poly-L-proline type, and may not all have the same amino-acid sequence. 96," Acid-stable cross links of at least two varieties are present in varying degree in different collagens. 98 Two 'typical building-stones of collagen, delta-hydroxylysine and 4-hydroxyproline, have attracted considerable study, since each has 16 possible stereoisomers.•9, • 0o A study using glycine-C TM led to the conclusion that albumins are the pre- decessors of skin collagens. TM X-ray studies under small incidence angles indicated that the cross striations of collagen are not results of the protein structure, but are caused by polysaccharides held to the protein chains by forces weaker than covalent bonds. •ø2 Collagens from different tissues showed varied degrees of resistance to cleavag• because of different surface films or coatings. •øa Chlorinated naphthalene, which produced hyper- keratosis in calves, also depressed plasma levels of vitamin A and ascorbic acid suggesting that the pathological changes in skin and connective 'iissues might be connected with those substances. TM The arnino-acid composition of elastoidin from the ceratotrichia of a shark justified its inclusion in the collagen group of proteins, but its high tyrosine and cystine content were cited as the possible basis of it• peculiar hydrothermal behaviour. •ø• Collagen treated with enzymes, acids, or alkalis formed networks of fibres resembling elastin.•ø•, •ø• Rats fed a diet containing 50 per cent Lathyrus odoratus meal developed aneurysms of the aorta, as a result of general lysis of elastic fibres. • o8

240 JOURNAL OF THE SOCIETY OF COSMETIC CHEMISTS ENZYME BIOSYNTHESIS AND STRUCTURE A useiul review on enzymes as units of biological structure and function was published in 1956 as the result of a symposium held in 1955. TM In another brief review of induced synthesis of enzymes the enzyme-forming system was visualised as a complex between ribonucleic acid, inducer, and enzyme, with simple components, probably amino acids, being drawn from a metabolic pool for synthesis on the template, which may be ribonucleic acid. TM Liver cell nucleoli were isolated and found to have properties sug- gesting that they furnish the templates for synthesis of the enzymes which govern mitosis.• Cytochrome C was studied by isolating the portion of the apoenzyme bound to the porphyrin two cysteine residues were found to be joined to the porphyrin by sulphide bridges, and a histidine residue next to one of the cysteines was believed to be bound to the iron through its imidazole' ring. • •2 ENZYME MECHANISM In a preliminary sketch of the principal features of a•theory of catalysis TM it was pointed out that all catalytic reactions are caused and directed by free valencies, with the catalyst playing a role not unlike that of a free radical. The fatty acid cycle was duplicated, using model compounds containing the structural elements considered important in coenzyme A activity. TM A possible analogue of enzyme action was seen in the "chain effect" of polysar- cosine ,dimethylamide in accelerating the polymerization of phenylalanine-N- carbonic anhydride the accelerating effect was proportional to the n amber of units in the polysarcosine molecules used. TM '. The transport of electrons over long chains of atoms appears to be involved in enzyme activity, and in macromolecules a distant transfer of ionisation is possible, not by a, small displacement of a, multitude of elementary charges,, but by a large displacement of relatively few charges along the molecules. m The electron transport systems of cell mitochondria are conceived to be quasi-conducting continua in which electrons originating in reduced diphosphopyridine nucleotide, and succinate are transferred ultimately to molecular oxygen. The various enzymes , of this semi~con- ductor system are linked to one another by bonds which permit resonance interaction throughout the entire structure in a manner not describable by classical kinetics. The many non-hem iron atoms present may act as conducting and structural links between the different oxidation-reduction units of the system. m Progress has been made in determining methods of attachment of enzymes to coenzymes and substrates. Kinetic studies supported the idea that primary amino groups of the old yellow enzyme serve as binding sites for the phosphoric acid residue of flavine mono-nucleotide. TM It was concluded that two carboxyl groups of glutamic acid combine with NH • or NH radicals