Limited proteolysis regulates massive degradation of glycinin, storage 11S globulin from soybean seeds: An in vitro model

The time course of glycinin hydrolysis by papain was followed using densitometry of SDS-PAGE patterns, quantification of the residual protein and determination of its molecular mass by gel filtration, and by other appropriate methods. The hydrolysis occurs in two steps. In the first step, a limited proteolysis was observed consisting of a gradual detachment of the α-chain C-terminal sequence region, leading to the formation of glycinin-P, a relatively stable proteolysis product retaining the primordial hexameric structure. Glycinin-P was found to be composed of the intact β-chains covalently bound with the C-terminally truncated α-chains lacking the helix domain, strand J', and the C-terminal disordered region. Glycinin-P is further hydrolyzed in the second step exclusively by a one-by-one mechanism. Comparison of the kinetics of the limited and one-by-one proteolyses analyzed separately indicated that the decrease of protein concentration by 24-25% in the first step occurs almost exclusively due to the decrease of the molecular mass of the residual protein. Thus, the onset of the one-by-one proteolysis is delayed, suggesting a regulatory role of the preceding limited proteolysis in the subsequent massive degradation of glycinin. Probable structural alterations of glycinin generated by this limited proteolysis are discussed.     

The Comparative Characteristics of Naturally Produced and Hatchery-Reared Juvenile Pink Salmon,Oncorhynchus gorbuscha (Walbaum, 1792), from Sakhalin Oblast

Russian Journal of Marine Biology - The body size and weight characteristics were analyzed and the morpho-physiological condition of the system of internal organs was studied in wild juvenile pink...     

Dynamic rearrangement of the filamentous actin network occurs during zoosporogenesis and encystment in the oomycete phytophthora cinnamomi

The organization of filamentous actin (F-actin) in living cells of the oomycete Phytophthora cinnamomi was determined during zoosporogenesis and zoospore encystment by microinjecting sporangia with fluorescently labeled phalloidin and observing resultant fluorescence by confocal microscopy. In multinucleate sporangia prior to the induction of cleavage, phalloidin labeling took the form of plaques which occurred mainly in the periphery of the sporangia. After induction of cleavage, phalloidin labeling showed that the plaques disappeared and that F-actin began to accumulate along the developing cleavage planes and around nuclei and water expulsion vacuoles. F-actin labeling was also observed near the plasma membrane in zoospores and young cysts but reverted to the plaque form in older cysts. Localization of F-actin close to the developing cleavage planes is consistent with the idea that actin microfilaments function in the positioning and expansion of the cleavage membranes. Observations of plaques of actin in living sporangia provide evidence that plaques are not aldehyde-induced fixation artifacts. Copyright 1998 Academic Press.     

Serglycin expression during monocytic differentiation of U937-1 cells

Serglycin is the major proteoglycan in most hematopoietic cells, including monocytes and macrophages. The monoblastic cell line U937-1 was used to study the expression of serglycin during proliferation and differentiation. In unstimulated proliferating U937-1 cells serglycin mRNA is nonconstitutively expressed. The level of serglycin mRNA was found to correlate with the synthesis of chondroitin sulfate proteoglycan (CSPG). The U937-1 cells were induced to differentiate into different types of macrophage-like cells by exposing the cells to PMA, RA, or VitD3. These inducers of differentiation affected the expression of serglycin mRNA in three different ways. The initial upregulation seen in the normally proliferating cells was not observed in PMA treated cells. In contrast, RA increased the initial upregulation, giving a reproducible six times increase in serglycin mRNA level from 4 to 24 h of incubation, compared to a four times increase in the control cells. VitD3 had no effect on the expression of serglycin mRNA. The incorporation of (35S)sulfate into CSPG decreased approximately 50% in all three differentiated cell types. Further, the (35S)CSPGs expressed were of larger size in PMA treated cells than controls, but smaller after RA treatment. This was due to the expression of CSPGs, with CS-chains of 25 and 5 kDa in PMA and RA treated cells, respectively, compared to 11 kDa in the controls. VitD3 had no significant effect on the size of CSPG produced. PMA treated cells secreted 75% of the (35S)PGs expressed, but the major portion was retained in cells treated with VitD3 or RA. The differences seen in serglycin mRNA levels, the macromolecular properties of serglycin and in the PG secretion patterns, suggest that serglycin may have different functions in different types of macrophages.      

<Emphasis Type="Italic">α</Emphasis>-Amylase inhibitor-1 gene from <Emphasis Type="Italic">Phaseolus vulgaris</Emphasis> expressed in <Emphasis Type="Italic">Coffea arabica</Emphasis>plants inhibits α-amylases from the coffee berry borer pest

Background  

Coffee is an important crop and is crucial to the economy of many developing countries, generating around US70 billion per year. There are 115 species in the < i > Coffea < /i > genus, but only two, < i > C. arabica < /i > and < i > C. canephora < /i > , are commercially cultivated. Coffee plants are attacked by many pathogens and insect-pests, which affect not only the production of coffee but also its grain quality, reducing the commercial value of the product. The main insect-pest, the coffee berry borer ( < i > Hypotheneumus hampei < /i > ), is responsible for worldwide annual losses of around US70 billion per year. There are 115 species in the Coffea genus, but only two, C. arabica and C. canephora, are commercially cultivated. Coffee plants are attacked by many pathogens and insect-pests, which affect not only the production of coffee but also its grain quality, reducing the commercial value of the product. The main insect-pest, the coffee berry borer (Hypotheneumus hampei), is responsible for worldwide annual losses of around US500 million. The coffee berry borer exclusively damages the coffee berries, and it is mainly controlled by organochlorine insecticides that are both toxic and carcinogenic. Unfortunately, natural resistance in the genus Coffea to H. hampei has not been documented. To overcome these problems, biotechnological strategies can be used to introduce an α-amylase inhibitor gene (α-AI1), which confers resistance against the coffee berry borer insect-pest, into C. arabica plants.     

9-(Adenylyl)alkylcobalamins as inhibitors of adenosylcobalamin-dependent glycerol dehydratase from Aerobacter aerogenes

The behavior of two coenzyme analogs, [(5-aden-9-yl)methoxyethyl] cob (III) alamin and [(5-aden-9-yl)pentyl] cob (III) alamin modified at the nucleoside ligand sugar moiety was studied in the system of adenosyl-cobalamin-dependent glycerol dehydratase from Aerobacter aerogenes. It was shown that neither of the analogs possesses coenzyme properties and that both are strong competitive inhibitors for adenosylcobalamin (AdoCbl). The affinity of the two analogs for the apoenzyme is higher than that of AdoCbl. The data obtained are indicative of the essential role of the ribofuranoside fragment of AdoCbl in the manifestation of the coenzyme activity. The apoenzyme interaction with the analogs under study is discussed in terms of the Dreiding stereomodels for AdoCbl and its analogs.     

A study of water autodiffusion in model biological membranes, oriented lipid bilayers

The autodiffusion of water in a multibilayer structure formed by dipalmitoyl phosphatidylcholine and oriented on glass plates was studied by the method of NMR with magnetic field pulse gradient. It was shown that water molecules occur in several states differing in the degree of interaction with lipid molecules. A spectrum of the coefficients of water autodiffusion in a direction transversal to bilayers was found. The use of samples with different distances between the plates and an analysis of the dependence of the mode of diffuse decay of spin echo on diffusion time and the orientation of the sample, as well as measurements at temperatures above and below the gel-liquid crystal phase transition in cholesterol-containing samples enabled one to discriminate the diffuse decay component responsible for the transbilayer movement of water. The coefficient of bilayer permeability was estimated using the Tanner model. It was shown that the formation of mechanical defects ("cracks") in plane oriented bilayers is the most probable reason for the presence of the water component with the relatively high coefficient of diffusion.