Measurement of products from X-irradiated glycylglycine in oxygen-free aqueous solutions.

The product yields in X-irradiated aqueous solutions of glycylglycine (0.05 M and 1.0 M) were measured under deoxygenated conditions. Comparison was made between the results obtained from X- and 60Co gamma-irradiated glycylglycine solutions reported by Garrison, Sokol, and Bennett-Corniea (Radiat. Res. 53, 376-384, 1973). The mechanisms proposed by Garrison et al. were tested by evaluating the stoichiometric relationships. The two intermediate radicals, deamination and H-abstraction radicals, were produced in the initial interactions of glycylglycine with reactive species (e-aq, OH, H) formed in H2O. Although the difference was fairly large at 0.05 M, the production of deamination radicals agreed well with the consumption of the radicals at 1.0 M. The production and the consumption of H-abstraction radicals were within the estimated experimental error in dilute solutions. Among all the products only the G value of aspartic acid decreased with increasing concentration of glycylglycine. This could be attributed to the fact that more acetylglycine is formed at the expense of aspartic acid at 1.0 M than at 0.05 M glycylglycine solutions. Competitive reactions involved with deamination radicals under conditions of homogeneously distributed reactants are discussed to elucidate the radiation chemistry of glycylglycine.

Comparative free-radical chemistry in the radiolytic deamination and dephosphorylation of bio-organic molecules. I. Oxygen-free solutions.

A wide range of experimental data is evaluated in support of the hypothesis that the reductive deamination of amino acids and peptides by eaq- and the oxidative dephosphorylation of glycol phosphates by OH in oxygen free solution are related in terms of a common elimination reaction involving free-radical intermediates of the same genre, that is, XCH(R)C(OH)R----HX + CH(R)COR where X = NH2, RCONH, and H2PO4 respectively. The proposed reaction model unifies for the first time the basic free-radical chemistry of N-C and PO-C bond cleavage in the radiolysis of peptides and glycol phosphates including proteins and nucleic acids in oxygen-free solution.

Comparative free radical chemistry in the radiolytic deamination and dephosphorylation of bio-organic molecules. II. Oxygenated solutions.

The radiolytic deamination and dephosphorylation of peptides and phosphate esters in oxygenated solutions are OH-induced and involve the formation and subsequent degradation of the peroxyl radicals RCONHC(O2)R2 and POC(O2)R2 respectively. Reaction analogues in the degradation chemistry of these peroxyl intermediates from various peptides and phosphate esters including protein and DNA are evaluated in detail. The evidence is that the reaction mechanisms recently proposed for removal of POC(O2)R2 radicals in the radiolytic scission of the DNA strand are identical in form with the mechanisms identified in earlier studies of RCONHC(O2)R2 radicals in the radiolytic cleavage of the peptide chain. The analogy includes the chemical forms of the final products and their specific yields.

Detection of faking on the Tennessee Self-Concept Scale.

The Tennessee Self Concept Scale (TSCS) was administered to a subject of 352 university students under standard administration conditions. Four other subsets responded under conditions designed to induce moderate and maximum faking in both positive and negative directions. Members of a sixth subset ("Sleepers") responded irrelevantly to from 10% to 50% of the TSCS items. Multiple discriminant analysis of the faked responses, using Column and Self-Criticism scores as predictors, supported a two-dimensional interpretation of the TSCS (self-concept and self-criticism). Analysis of classification errors showed the greatest confusion resulted from classification of Fake-Good respondents into the Standard group. Rasch analysis of sleeper responses was relatively insensitive to implausible response subsets. A second study (n = 413) supported conclusions of the first, and exploratory analyses suggested the possibility that a "Faking Score" may be developed using a set of specific item responses rather than subscale scores.