Polypeptidyl derivatives of bovine pancreatic ribonuclease
(RNase) containing two or three tyrosine chains
with an average of two to three residues per chain have
been prepared. The effects of various perturbants such as
neutral salts, ethanol, urea and guanidine hydrochloride
on the thermal transition of the derivatives have been
studied....
A comparative study was made on the effect of urea denaturation
of bovine serum albumin (BSA), polyglycyl BSA and poly-L-phenylalanyl
BSA. The denaturation process was followed by ultraviolet
spectrophotometry and optical rotation.
A blue shift in the absorption maximum at 278 mμ was observed
in urea denatured proteins, In 7M...
In order to understand more about insulin behavior in solution,
Zn-free insulin was modified by adding polyglycyl chains to the
molecule and then observing the effect of the peptide on the behavior
of insulin under various conditions.
NCA-glycine (N-Carboxyglycine anhydride) of high purity was
reacted with Zn-free insulin in aqueous...
In order to examine some possible tyrosyl interactions, poly-tyrosyl lysozyme and poly-O-methyltyrosyl lysozyme were prepared and their solubilities were compared. Both derivatives exhibited
similar pH dependent solubilities, showing a minimum solubility at
about pH 8. Their solubilities varied with temperature, having a
positive enthalpy of solution. The effect of a...
A heat stable derivative of bovine serum albumin containing
300 residues of glycine added to 30 sites on the surface of the protein
has been prepared. This derivative may be heated to 100° C for
prolonged periods of time without aggregation. By comparison,
native BSA aggregates at 62° C under...
Acetylimidazole was used to acetylate the tyrosyl residues
of insulin. The kinetics of acetylation were studied by termination of
the reaction at several time intervals, isolation of acetylated insulin
and determination of 0-acetyltyrosyl groups by deacetylation with
hydroxylamine. The deacetylation was also studied kinetically by
means of the absorbancy change...
The spectrophotometric titration of the tyrosine residues,
their reaction with N-acetylimidazole, and the effect of pH on the
thermally induced conformational transition of ribonuclease T₁ have
been investigated. The results of spectrophotometric titration in
0.20 M KCl/0.001 M sodium phosphate suggest that titration of the
tyrosine residues occurs in two...
The halophilic alkaline phosphatase of Halobacterium
salinarium has been purified to a specific activity of 3,000-3,200
units per mg of protein. The purification scheme consisted of
acetone and ammonium sulfate fractionations, and molecular sieving
and adsorption chromatography on Sephadex G -50. The enzyme was
stabilized during purification by the presence...
The thermophilic aldolase from Bacillus stearothermophilus
(NCA 2184) has been purified to a specific activity of 45.5 μ-moles
of fructose-1, 6-diphosphate cleaved per minute per mg of enzyme,
representing a 624-fold increase over the crude extract. The preparation appeared to be homogenous by sedimentation velocity ultra-centrifugation
and by a specific...