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Wool fibers and cloth damaged by mechanical action such as abrading and grinding show strong EPR signals. Silk fibers after grinding also show strong EPR signals. Both wool and silk ground in a dry nitrogen atmosphere exhibit a doublet spectrum attributed to a ·CH radical on the polypeptide chain. In wool, a complex curve centered at g = 2.025 is observed. It is attributed to a CH2S· radical resulting from the rupture of the disulfide bond in the cystine residue. These radicals are stable for many months in a nitrogen atmosphere or vacuum. In dry oxygen the spectrum of the ·CH radical is transformed within a few hours from a double into a single, narrow curve, whereas the spectrum characteristic of the cystine radical disappers more slowly. In the presence of water vapor both radical species are rapidly destroyed and their spectra disappear. The mechanisms for the production of free radicals by mechanical action are believed to be direct chain rupture or localized pyrolysis, coupled with migration to specific radical traps in the protein.

SUMMARY An as yet unidentified glucose-complex is formed in the cells of 5 mm stem segments cut from the third internode at 1 mm from the tip of etiolated pea seedlings. In segments growing in solutions containing 10 μg/ml IAA and various concentrations of glucose the quantities of the unknown glucose-complex and cellulose are proportional. Increasing the IAA concentration at a constant glucose concentration of 0.1% causes an increase in the glucose-complex and in the synthesis of cellulose up to a concentration of 10 μg/ml. At IAA concentrations higher than 50 μg/ml cellulose synthesis decreases to the value obtained when no IAA is present, whereas the amount of the glucose-complex is increased. Galactose inhibits cellulose synthesis by way of interfering with the glucose absorption. In low concentrations of glucosecobalt chloride promotes sugar absorption, the formation of the glucose-complex, and cellulose synthesis. In high sugar concentrations it does not affect these processes. The results obtained indicate a close relationship between cellulose synthesis and the formation of the glucose-complex. It is suggested that the latter is an intermediate in the synthesis of cellulose.

SUMMARY The influence of G.A. and I.A.A. on the hydroxyproline content of cell walls was examined with reference to the concept of wall-bound protein as a cross-linking agent regulating wall extensibility. It appeared that the hydroxyproline-rich protein content of cell walls pf elongating cells from the stems of two pea varieties, Alaska and Rondo, differed remarkably. In accordance with Lamport's hypothesis, the dwarf variety (Rondo) had a much higher hydroxyproline content than the standard variety (Alaska). When G.A. was applied to the top of the slow growing dwarf variety, the growth rate increased until comparable to the standard variety and the hydroxyproline content of the cell walls decreased somewhat. However, no linear relationship between growth stimulation and decreased hydroxyproline content existed. Experiments performed with excised elongating pea stem segments, grown in a culture solution containing phosphate buffer, showed that the hydroxyproline content of the cell walls increased considerably during an incubation time of 24 hours. IAA strongly inhibited this increase while stimulating elongation. However, a solution containing IAA and sugar caused the greatest elongation but also the greatest formation of hydroxyproline. It was concluded that cell extension and the hydroxyproline content of cell walls are not necessarily inversely correlated.

A number of organic compounds containing sulfur or selenium are known to be useful as antioxidants or radio‐protective agents because of their reactivity with free radicals. We have studied the electron paramagnetic resonance (EPR) of some aliphatic and aromatic sulfide and disulfide compounds and their selenium analogs uv‐irradiated at λ=2537 A in order to characterize and compare the free radicals produced. The irradiation and the EPR measurements were carried out at liquid nitrogen temperature. The EPR spectra obtained for these compounds fall into four categories characteristic of the four types of radical species found—alkyl radicals, benzyl‐type radicals, sulfur radicals, and selenium radicals. The selenium radical, which has not been previously observed, exhibits an asymmetric spectrum having an axially symmetric g factor, with g⊥=2.08 and g∥=2.12.

RESEARCH on the biochemical function of trace selenium in animal nutrition indicates it probably functions in lipid antioxidant and free radical acceptor reactions. Selenoprotein fractions from selenate-fed animals have up to 500 times the antioxidant activity of vitamin E (ref. 1). Selenoamino-acids were very effective in reducing free-radical damage to enzymes and amino-acids when aqueous solutions were exposed to ionizing radiation2. Woodbridge3 found organic selenium compounds to be powerful antioxidant agents. These unusual properties of selenium compounds in reacting with free radicals suggested that an electron paramagnetic resonance investigation of selenium amino-acids and antioxidants and their sulphur analogues would be of interest.