Studies on the heterogeneity of crystallized β-lactoglobulin

Abstract

While this paper was in the press, we noted the work of Werner & Odin (1952) on the reaction of diphenylamine with crystalline sialic acid. The absorption curve which they report for the coloured complex produced is very similar to that shown above in Fig. 4, and it appears likely that our method of estimating urinary mucoprotein depends mainly upon its sialic acid content.

Evidence for the chemical interaction of urease in solution

“…This conclusion is supported by the appearance of the centrifuge diagrams, which show clearly that the concentration gradient falls to zero between the peaks, thereby implying independence of the flow of each component (Gilbert, 1959; Williams, Van Holde, Baldwin & Fujita, 1958). This behaviour may be compared with that of such systems as ac-chymotrypsin (Massey, Harrington & Hartley, 1955) and P-lactoglobulin (Ogston & Tilley, 1955), where rapid equilibration occurs between monomer and polymers. In respect of (b), the mechanism of polymerization, intermolecular disulphide bridges could arise either by direct oxidation of sulphydryl groups on separate molecules or by the mercaptan-disulphide interchange, originally proposed by Huggins et al (1951) to account for the gelation phenomena encountered with plasma albumin in urea solutions.…”

The solubility and fractionation of β1-lactoglobulin

“…U-tube electrophoresis. A Hilger Tiselius apparatus was used as described by Ogston & Tilley (1955). The 3-5 ml.…”

“…The current was always 10 mA at about 400v. Boundaries were divided to estimate 'fast' and 'slow' components according to the method of Ogston & Tilley (1955).…”

“…Among previous workers only Ogston & Tilley (1955) made efforts to ensure that milk from single cows was used for their preparations, and they were able to distinguish 'normal' and 'abnormal' types of lactoglobulin. The 'normal' type (identified as ,llactoglobulin by Ogston & Tombs, 1957) gave a boundary pattern indicating two components on U-tube electrophoresis at pH 4-66, while the proportion of slow component varied with protein concentration down to a limit of 20 % at high concen-trations.…”

A Method for the Quantitation of Charge by Size Exclusion Chromatography Demonstrated with Components of Ficoll 400

“…[44] Stokes radius (R s /nm) = 2.89 l 0.05 for the dimer below pH 7.0; based on diffusion coefficients [47,52 -55] and sedimentation coefficients [43,[56][57][58] in combination with a chain molecular mass of 18 400, [59] weight average sedimentation equilibrium of 37 100 [47] and partial specific volume of 0.751 mL g -1 . [47] In spite of reproducibly different s-values between low pH and neutral pH only an average Stokes radius can be given with statistical significance for the dimer below pH 7.0.…”