Analysis of ligand-binding data by lambda invariance testing.

A method for analyzing data for one or two classes of homogeneous binding sites is presented. It uses moments of exponentially depressed data. From these the binding parameters are calculated as a function of the depression.

Robust estimation in pulse fluorometry. A study of the method of moments and least squares.

Most laboratories use least-squares iterative reconvolution (LSIR) as a routine method for estimating decay parameters in pulse fluorometric data. It is shown here, however, that LSIR is very sensitive to small amounts of error in the data whenever two decays become too close to one another, or whenever analyses of three decays are attempted. In such cases, inferior methods of estimating integrals, small zero point shifts, or small errors in the measured exciting light will result in failures of least squares, where the method of moments, with moment index displacement and lambda invariance testing, will succeed.

The organization of oligonucleosomes in yeast.

We have developed a method of preparing yeast chromatin that facilitates the analysis of nucleoprotein organization. Yeast chromatin, isolated as an insoluble complex, is digested with micrococcal nuclease and fractionated into major insoluble and soluble fractions. No nucleosomal repeat is seen early in digestion for the insoluble fraction.

Immunochemical detection of chromosomal protein HMG-17 in chromatin subunits.

Chromosomal protein HMG-17, purified from calf thymus, has been used to elicit specific antibodies in rabbits. Specific serological reaction between the antigen and the antisera is demonstrated by solid-phase radioimmunoassay and by competitive inhibition assays. The antisera did not cross-react with histones or other chromosomal HMG proteins.

High mobility group proteins of Saccharomyces cerevisiae.

The yeast Saccharomyces cerevisiae contains four proteins having amino acid compositions typical of the high mobility group (HMG) proteins. Three of these are eluted from chromatin by 0.35 M NaCl; one is not, but it is eluted by 0.

Analysis of nonexponential fluorescence decay data by a method of moments.

A method of moments is presented for the analysis of convoluted fluorescence decay data when the impulse response function is given by f(t) = alpha exp (-At - Bt1/2). Examples of this method are given using both simulated and measured fluorescence decays. It is also shown that this method, used with moment index displacements, will correct for light-scatter leakage, zero-point time shifts, and slow lamp drift.

Preparative gel electrophoresis: detection, excision, and elution of protein bands from unstained gels.

Methods are described for localizing proteins in unstained gels and accurately excising the regions containing them. A gel elutor, which is all glass with Lucite fittings, is also described. The elutor removes proteins from gels with a high yield and concentrates the protein in a small volume.

Yeast inner histones and the evolutionary conservation of histone-histone interactions.

The inner histones of the yeast, Saccharomyces cerevisiae, have been isolated and identified by their amino acid compositions. H4 appears to be close to its calf and pea counterparts. H2a, H2b, and H3 have diverged.

Immunological relatedness of high mobility group chromosomal proteins from calf thymus.

The non-histone proteins HMG-1, HMG-2, HMG-3, HMB-8, HMG-14, and HMG-17 (Goodwin, G. H., SANDERS, C.

Cross-complexing pattern of plant histones.

Pea histones H2a, H2b, H3, and H4 have been isolated and their interactions studied by fluorescence anisotropy, light scatter, and circular dichroism. Histones H3 and H4 are almost identical in plants and animals, but plant histones H2a and H2b differ markedly from their mammalian counterparts. Pea H2b has a molecular weight approximately 20% greater than that of calf thymus H2b; the amino acid compositions of the two proteins are different.

Interactions between the subfractons of calf thymus H1 and nonhistone chromosomal proteins HMG1 and HMG2.

The nonhistone chromosomal proteins, HMG1 and HMG2, interact with the various subfractions of calf thymus H1 with a high degree of specificity. Subfractions 1b and 2 interact very strongly with HMG1 to form heterodimers. In contrast, subfractions 3a and 3b interact much more weakly.

Conformational changes in subfractions of calf thymus histone H1.

This paper presents the first study of conformational changes in the subfractions of calf thymus H1. H1 was fractionated by the method of Kincade and Cole (Kincade, J. M.

Physical studies of the nonhistone chromosomal proteins HMG-U and HMG-2.

The nonhistone chromosomal proteins, HMG-1 and HMG-2, have a folded conformation, with a high alpha-helical content, over a wide pH range. At high and low pH values, the molecules unfold. Both molecules contain cysteine and tryptophan.

On the analysis of circular dichroic spectra of proteins.

A new method is presented for analyzing circular dichroism spectra. The method employs integrals over the data and calculates the alpha-helical, beta-sheet, and random coil content of the proteins from such integrals. It is shown that the analyzed alpha-helical content is usually reliable to within 5%, beta-sheet values are somewhat less reliable, and random coil values are least reliable.