The kinetics of iodination at the 3-position of 1.3-dirnethyland [3-2HI]-1 ,3-dimethyl-indolin-2-one are reported for buffered mildly alkaline 50% (w /w) aqueous methanol solutions at 25". Unlike the iodination of many ketones these reactions (even in the presence of excess of substrate and with large amounts of added iodide ion) do not follow a zero-order rate expression, but show behaviour in...

Children with protein calorie malnutrition have impaired immune functions. Immunoglobulin levels are low in children with severe protein deprivation, but are not affected in moderate or borderline protein malnutrition. Specific antibody response is either normal or reduced depending on the antigen used. Involution of the thymus dependent lymphatic system and severe impairment of the cell-mediat...

The reactivities of the tyrosyl residues of calf and rabbit cytochrome bs have been examined by acylation, iodination, and titration of the proteins. These experiments distinguish residues 6 and 7 as the most exposed and reactive residues, which ionize normally and can be acetylated or iodinated to form the monoiodo or diiodo derivatives. Tyrosine 30, which is common to both cytochrome preparat...

Six different proteins are found to be reproducibly exposed on the cell surface of chicken embryo fibroblasts (CEF) by the criterion of lactoperoxidase-catalyzed iodination (250,000, 185,000, 130,000, 100,000, 87,000, and 75,000 daltons). We wondered whether cell enucleation might lead to a differential partition of these surface proteins with the karyoplast or cytoplast membrane. We found that...

The mode of interaction of Cro repressor with specific and nonspecific sites on DNA was explored by chemical modification and protection of lysine and tyrosine residues. Cro has 8 lysines. In the presence of DNA, lysines 32 and 56 are fully protected and lysines 21, 62, and 63 are partially protected from alkylation. However, the terminal amino group and lysines 8, 18, and 39 are not protected....

Conditions were established where the thallium-catalyzed iodination of random coil DNA proceeded 100-200 times faster than for native DNA. This reaction was explored as a probe for localized regions of disrupted base pairs in duplex DNA. A heteroduplex was constructed between DNA fragments produced by Hind II + III cleavage of phi80 plac DNA and phi80 plac DNA containing the Ll deletion (73 nuc...

Iodinated derivatives of adrenocorticotropic hormone (ACTH) were prepared with the use of NaI and chloramine-T and isolated by isoelectric focusing. The monoiodinated derivative (p1 7.6) was resolved into [monoiodoTyr2]ACTH and [monoiodoTyrZ3]ACTH by chromatography on columns of carboxymethylcellulose. Both monoiodo-AC’IH species exhibited only 30% of the maximum hormonal activity when assayed ...

Sindbis virus was iodinated by using the enzyme lactoperoxidase, an iodination technique which labels only surface proteins. By this technique, the two viral glycoproteins are labeled, and the internal viral protein is not. The two glycoproteins are iodinated to strikingly different extents. This difference in susceptibility to iodination apparently is due to the position or conformation of the...

Brucella abortus releases two components (fractions 3b and 10) that inhibit the myeloperoxidase-H2O2-halide antibacterial system of bovine neutrophils by inhibiting degranulation. Fractions 3b and 10 were analyzed by high-performance liquid chromatography and thin-layer chromotography and compared with nucleotide and base standards. These investigations indicated that fraction 3b coeluted and c...

Surface-exposed proteins of vinblastine-sensitive human lymphoid cell line of leukemic origin (CCRF-CEM) were exam ined by the lactoperoxidase-catalyzed iodination and two-di mensional polyacrylamide gel electrophoresis methods. Spots which comigrate with bovine brain tubulin and rabbit muscle actin were prominently labeled in the whole membrane but not in the high-speed supernatant fraction of...