Christian B. Anfinsen

Bio: Christian B. Anfinsen is an academic researcher from United States Public Health Service. The author has contributed to research in topics: Albumin & Ovalbumin. The author has an hindex of 10, co-authored 10 publications receiving 1720 citations.

The gel-filtration behaviour of proteins related to their molecular weights over a wide range

Abstract: 1. Correlation between elution volume, V(e), and molecular weight was investigated for gel filtration of proteins of molecular weights ranging from 3500 (glucagon) to 820000 (alpha-crystallin) on Sephadex G-200 columns at pH7.5. 2. Allowing for uncertainties in the molecular weights, the results for most of the carbohydrate-free globular proteins fitted a smooth V(e)-log(mol.wt.) curve. In the lower part of the molecular-weight range the results were similar to those obtained with Sephadex G-75 and G-100 gels. 3. V(e)-log(mol.wt.) curves based on results with the three gels are taken to represent the behaviour of ;typical' globular proteins, and are proposed as standard data for the uniform interpretation of gel-filtration experiments. 4. Some glycoproteins, including gamma-globulins and fibrinogen, do not conform to the standard relationship. The effect of shape and carbohydrate content on the gel-filtration behaviour of proteins is discussed. 5. As predicted by the theoretical studies of other authors, correlation exists between the gel-filtration behaviour and diffusion coefficients of proteins. 6. The lower molecular-weight limit for complete exclusion of typical globular proteins from Sephadex G-200 varies with the swelling of the gel, but is usually >10(6). 7. The concentration-dependent dissociation of glutamate dehydrogenase was observed in experiments with Sephadex G-200, and the sub-unit molecular weight estimated as 250000. The free sub-units readily lose enzymic activity. 8. Recognition of the atypical gel-filtration behaviour of gamma-globulins necessitates an alteration to several molecular weights previously estimated with Sephadex G-100 (Andrews, 1964). New values are: yeast glucose 6-phosphate dehydrogenase, 128000; bovine intestinal alkaline phosphatase, 130000; Aerobacter aerogenes glycerol dehydrogenase, 140000; milk alkaline phosphatase, 180000.

Application of a Theory of Enzyme Specificity to Protein Synthesis

Abstract: The suggestion of Lipmann' that the energy required to drive this reaction to the right came from adenosine triphosphate has been supported by the extensive work2 which has been discussed by the previous speakers on this symposium. While the detailed mechanism of this energy transfer has not been fully elucidated, the ATP apparently forms an amino acid anhydride. The fact that an anhydride of relatively high-energy content is the method of driving the reaction thermodynamically fits in with organic practice in which acyl anhydrides are the usual reagents for acylations. In addition to thermodynamic activation, there is a needed \"kinetic activation.\" For example, the acyl phosphates and acyl adenylates acylate amines non-enzymatically at appreciable rates in aqueous solution,3 but this reaction is certainly not rapid enough or selective enough to account for protein synthesis. The reaction of these acyl anhydrides to form peptides must be catalyzed, and it is this catalysis which is the subject of this paper. An analysis of why this linking of amino acids presents such formidable difficulties is revealing. The difficulty appears to be caused by a combination of requirements, each of which, taken singly, is rather easily satisfied. The first requirement is that an individual position in the protein be occupied by one and only one amino acid. This by itself is not a difficult condition to satisfy, since enzymatic reactions of equally high specificity are well known. The second requirement is that a highmolecular-weight polymer be produced. Again, this, by itself, is not a unique condition, since the enzymatic formation of high-molecular-weight molecules from a given monomer is also familiar, e.g., carbohydrate polymerization catalyzed by phosphorylases. Finally, the macromolecule is formed from many different monomer units, but this requirement is also easily achieved if the units are randomly arranged, e.g., polynucleotide formation by polynucleotide phosphorylase.4 However, the combined requirements, i.e., the synthesis of a macromolecule from many individual monomers to give a single specified sequence, is a problem of different magnitude. A mechanism involving an individual enzyme for each bond would be acceptable from the specificity point of view, but it would require an inconceivably large number of enzymes to form all the proteins of the cell. Moreover, there are other observed conditions, e.g., the necessity of feeding all the amino acids

Serum and urinary lysozyme (muramidase) in monocytic and monomyelocytic leukemia

Abstract: Markedly increased quantities of lysozyme have been found in the serum and urine (ranging to 2.6 g per day) of ten consecutive cases of monocytic and monomyelocytic leukemia. The enzyme has been isolated from the urine of several cases and physicochemically and immunochemically characterized. It is apparently identical to the lysozyme of normal tears, saliva, leukocytes, and serum, but structurally different from the lysozyme of hen's egg white. The activity of the human enzyme assayed with M. lysodeikticus organisms is 3 to 12 times greater than egg white lysozyme at equivalent concentrations. An agar plate method has been developed for quantitating lysozyme activity in small samples (approximately 25 µl) of serum, urine, or other biological fluids. The range and reproducibility of this method were found to be superior to previously available lysozyme assay procedures. Present evidence indicates that lysozyme is the principal, if not the sole, product of the proliferating monocytes in monocytic and monomyelocytic leukemia, and quantitation of serum and urine lysozyme should be a useful diagnostic procedure for these leukemias.