S-oxalylglutathione is a substrate for gamma-glutamyltransferase (GGT). Implications for the role of GGT in cell proliferation

With glycylglycine or water as acceptor, bovine kidney gamma-glutamyltransferase catalyzes reactions of the known mammalian metabolite, S-oxalylglutathione, at rates comparable to those of L-gamma-glutamyl-p-nitroanilide, a known good substrate. N-Oxalyl-cysteinylglycine is the eventual product of the former reaction. Since oxalyl thiolesters are implicated as important cell proliferation inhibitors, it is proposed that this reaction plays a major role in controlling cell proliferation.     

The phosphorylation of adrenal proteins in response to adrenocorticotropic hormone

The phosphorylation of rat adrenal protein components in response to adrenocorticotropin has been studied in adrenal quarters, isolated cells, and in vivo. In adrenal quarters, adrenocorticotropic hormone (ACTH)-stimulated phosphorylation or dephosphorylation of proteins was not affected by the presence of protein synthesis inhibitors despite a total inhibition of steroidogenesis. (The term dephosphorylation refers to an apparent decrease in the labeling of a particular protein with 32P at various times after the addition of ACTH. This may be due to enzymatic removal of phosphate or protein degradation or complexation of this protein with another cellular component.) Studies with isolated cell preparations identified several proteins that are phosphorylated or dephosphorylated in response to hormone. These changes in phosphorylation were also observed in adrenal quarters and correlated well with ACTH-stimulated steroidogenesis as determined by temporal analysis and dose-response studies of corticosterone production. In vivo injection of male hypophysectomized rats with [32P]phosphate and ACTH demonstrated changes in the labeling of six adrenal proteins. Many of the proteins phosphorylated in vivo were also demonstrated to be phosphorylated in both in vitro systems. Finally, the injection of a physiological dose of ACTH appeared to selectively activate the type I cAMP-dependent protein kinase within the microsomal fraction as determined by the binding of a photoaffinity-labeled reagent. These results suggest that alterations in phosphorylation of adrenal proteins in response to ACTH is proximal to or independent of the obligatory role of protein synthesis in acute steroidogenesis.     

Widespread occurrence of AP in amyloidotic tissues. An immunohistochemical observation

Plasma (P)-component of amyloid (AP or SAP), while not an integral part of the amyloid fibril, has been considered to be intimately associated with virtually every different type of amyloid. In the present study, we evaluated the distribution of AP in the organs frequently involved in two forms of human systemic amyloidosis (AA and AF) and in mouse AA amyloidosis, by use of immunohistochemistry with anti-AP. Although the amyloid deposits generally showed moderate reactions with anti-AP, they were not always clearly distinguished from the surrounding non-amyloid tissue elements which often stained as well. The basement membrane often showed even stronger reaction to anti-AP than the adjacent amyloid deposits, and liver sections demonstrated such a high overall reaction to anti-AP that the anti-AP reaction on the amyloid deposits was often obscurred. The present results suggest that the binding between AP and the amyloid fibril may not be monospecific, that AP by this technique occurs rather widely throughout the body, and therefore that anti-AP may not be considered as specific a marker for amyloid deposits in immunohistochemical and perhaps other studies as well.     

In vivo experimental modelling of the infectious process caused by stable L forms of the causative agent of typhoid

To simulate the infectious process and to study the persistence of L-forms, rabbits and guinea pigs were infected with S. typhi stable L-forms. The materials presented in this work indicate that both subconjunctival and intraperitoneal infection led to the development of the clinically indistinct, but morphologically pronounced pathological process with characteristic localization and typical changes in the gastrointestinal tract. The typical features of the process were the generalized immunomorphological reaction of the lymphoid apparatus with the appearance of light-colored reticulomacrophagal elements, the signs of the activation of humoral and cell-mediated immunity and the formation of small epitheloidocellular granulomas. The results of the investigation indicate that the stable cultures of S. typhi L-forms are highly pathogenic and capable of inducing the infectious process in experimental animals.     

Faster evolution of highly conserved DNA in tropical plants

A faster rate of nuclear DNA evolution has recently been found for plants occupying warmer low latitudes relative to those in cooler high latitudes. That earlier study by our research group compared substitution rates within the variable internal transcribed spacer (ITS) region of the ribosomal gene complex amongst 45 congeneric species pairs, each member of which differed in their latitudinal distributions. To determine whether this rate differential might also occur within highly conserved DNA, we sequenced the 18S ribosomal gene in the same 45 pairs of plants. We found that the rate of evolution in 18S was 51% faster in the tropical plant species relative to their temperate sisters and that the substitution rate in 18S correlated positively with that in the more variable ITS. This result, with a gene coding for ribosomal structure, suggests that climatic influences on evolution extend to functionally important regions of the genome.     

Porcine high molecular weight kininogen: its purification and properties as a thiol proteinase inhibitor as compared to human high molecular weight kininogen

1. High mol. wt kininogen (HMW kininogen) was purified to a homogeneous state from porcine plasma. 2. The protein exhibited a strong inhibitory activity for thiol proteinases such as ficin, papain and calpain I, whereas it did not inhibit serine proteinases, trypsin and chymotrypsin. 3. The mol. wt, isoelectric point, amino acid and carbohydrate compositions, stabilities to temperature and pH, kinetic constants, and immunological properties of the porcine HMW kininogen were determined and compared with those of human HMW kininogen.     

Comparative study of the effect of L-lysine-L-oxidase from Trichoderma harzianum Rifai and Trichoderma viride on nucleic acid synthesis in human tumor cells in vitro

L-lysine-alpha-oxidase, a new fungal enzyme catalyzing oxidative deamination of L-lysine, exerts an inhibitory effect on DNA, RNA and protein synthesis in human cells of carcinoma ovarius (CaOv) in vitro.     

Solid-phase synthesis of polymyxin B1 and analogues via a safety-catch approach.

As part of a program towards the development of novel antibiotics, a convenient method for solid-phase synthesis of the cyclic cationic peptide polymyxin B1 and analogues thereof is described. The methodology, based on cleavage-by-cyclization using Kenner's safety-catch linker, yields crude products with purities ranging from 37-67%. Antibacterial assays revealed that analogues 23-26, in which the (S)-6-methyloctanoic acid moiety is replaced with shorter acyl chains, exhibit distinct antimicrobial activity. The results suggest that the length of the acyl chain is rather critical for antimicrobial activity. On the other hand, substitution of the hydrophobic ring-segment D-Phe-6/Leu-7 in polymyxin B1 with dipeptide mimics (i.e. analogues 27-33) resulted in almost complete loss of antimicrobial activity.