Curtis M. Wilson

Studies and critique of Amido Black 10B, Coomassie Blue R, and Fast Green FCF as stains for proteins after polyacrylamide gel electrophoresis.

Abstract The properties of amido black 10B (C.I. 20470), Coomassie blue R (C.I. 42660), and fast green FCF (C.I. 42053) as protein stains, along with a few comments on Coomassie blue G (C.I. 42655), are presented and dye impurities and their effects on protein-dye binding within gels are discussed. All three dyes produced metachromatic effects with some proteins. Problems encountered with long-term stability and fixation of certain maize seed proteins are reported along with procedures for overcoming them. The low solubility of Coomassie blue R in trichloroacetic acid prevented maximum staining and destaining within a reasonable time, whereas other solvents allowed diffusion of some proteins during staining. Coomassie blue R binds to proteins in much higher amounts than do amido black and fast green, which accounts for its sensitivity in detection of protein bands in gels. Procedures for obtaining maximum contrast with photographs are also outlined.

Chromatographic separation of ribonucleases in corn.

Abstract Two RNAases have been isolated from corn seedlings by chromatography on carboxymethylcellulose. RNAase A, secreted from the scutella and found in root supernatant solutions, is eluted by pH-6.0 buffer. RNAase B is eluted by pH-8.0 buffer. RNAase B is adsorbed onto mitochondria, but may be removed by 0.5 M KCl. RNAase A has a pH optimum at 5.0 and RNAase B at 6.2. Both RNAases are stimulated by KCl at their optimum pH. RNAase A is stimulated by MgCl 2 at pH 5.0 and inhibited at pH 5.8, whereas RNAase B is stimulated at pH 5.8. A third RNAase, similar to RNAase A in chromatographic behavior and to RNAase B in pH optimum, was isolated, but it may be an artifact of isolation. It is suggested that the RNAases have different functions.

Metabolism of lysine and leucine derived from storage protein during the germination of maize

Abstract The metabolism of [U- 14 C]leucine or [U- 14 C]lysine during the germination of maize was studied using seed in which the storage protein was labelled. The labelled amino acids were injected below the ear of maize plants during seed development. The storage protein contained a large excess of leucine but insufficient lysine for synthesis of new protein in the developing axis. The axis preferentially utilized leucine and lysine (and possibly proline) derived from storage protein for synthesis of new protein. Excess leucine was respired as CO 2 with little conversion to other amino acids. The lysine deficit was met by synthesis of new unlabelled carbon skeletons.

Mapping of Zein Polypeptides After Isoelectric Focusing on Agarose Gels

Isoelectric focusing of zein in agarose gels gives sharp separations of at least 25 bands noted among 25 corn-belt inbreds. Six inbreds provided standard bands which were used to construct a pattern map. A method is provided for comparing bands, identified by distance from the cathode, which differ only slightly in position. The 25 inbreds were separated into five groups on the basis of pattern similarity. Some groups contained inbreds derived from widely different sources. Zein isoelectric focusing in agarose should be useful for genotype identification and for determination of varietal purity.

Plant nucleases. IV. Genetic control of ribonuclease activity in corn endosperm.

Ribonuclease activity in the endosperms of 14 corn (Zea mays L.) inbreds ranged from 285 to 1305 units/g fresh weight 50 days after pollination. Activity is low in the inbred M14 and high in the inbred WF9. Hybrid endosperms contain intermediate levels of ribonuclease, and segregation occurs in the F2 generation. The ribonuclease contents of the opaque-2 versions of nine inbred lines ranged from 1288 to 5110 units/g. The floury-2 mutation apparently does not affect ribonuclease content. Two or more genes may be involved in the control of ribonuclease content of developing endosperms.