scholarly journals A systematic series of synthetic chromophoric substrates for aspartic proteinases

1986 ◽  
Vol 237 (3) ◽  
pp. 899-906 ◽  
Author(s):  
B M Dunn ◽  
M Jimenez ◽  
B F Parten ◽  
M J Valler ◽  
C E Rolph ◽  
...  
Keyword(s):  
Structure Function ◽  
Peptide Bond ◽  
Water Soluble ◽  
Animal Origin ◽  
Aspartic Proteinases ◽  
Peptide Substrates ◽  
Representative Selection ◽  
Micro Organisms ◽  
Hydrolysis Of ◽  
Selection Of

The hydrolysis of the chromogenic peptide Pro-Thr-Glu-Phe-Phe(4-NO2)-Arg-Leu at the Phe-Phe(4-NO2) bond by nine aspartic proteinases of animal origin and seven enzymes from micro-organisms is described [Phe(4-NO2) is p-nitro-L-phenylalanine]. A further series of six peptides was synthesized in which the residue in the P3 position was systematically varied from hydrophobic to hydrophilic. The Phe-Phe(4-NO2) bond was established as the only peptide bond cleaved, and kinetic constants were obtained for the hydrolysis of these peptide substrates by a representative selection of aspartic proteinases of animal and microbial origin. The value of these water-soluble substrates for structure-function investigations is discussed.

SOME FACTORS AFFECTING THE SURVIVAL OF RHIZOBIUM TRIFOLII ON WHITE CLOVER

1976 ◽  
pp. 182-186 ◽  
Author(s):  
C.N. Hale
Keyword(s):  
Seed Coat ◽  
White Clover ◽  
Inhibitory Effect ◽  
Water Soluble ◽  
Rhizobium Trifolii ◽  
Factors Affecting ◽  
Naturally Occurring ◽  
Clover Seed ◽  
Micro Organisms ◽  
Selection Of

Survival of Rhizobium trifolii on white clover seed before sowing is adversely affected by both drying and a water-soluble toxin which diffuses from the seed coat during the inoculation process. Survival of rhizobia is increased by removal of the toxin by seed washing or the suppression of its inhibitory effect by treatment of seed with phenolic adsorbents. Survival of rhizobia introduced into tbe soil on seed before the rhizosphere is capable of supporting growth and multiplication may be affected by the toxic diffusate and competition and/or antagonism from naturally occurring populations of soil micro-organisms, Selection of effective strains of rhizobia on criteria such as survival and competition abilities, as well as on the ability to nodulate and fix nitrogen, is considered to be extremely important.

scholarly journals A new chromophoric substrate for penicillopepsin and other fungal aspartic proteinases

1982 ◽  
Vol 203 (3) ◽  
pp. 603-610 ◽  
Author(s):  
Theo Hofmann ◽  
Robert S. Hodges
Keyword(s):  
Catalytic Efficiency ◽  
Aspartic Proteinase ◽  
Spectrophotometric Assay ◽  
Water Soluble ◽  
Burst Release ◽  
Penicillium Roqueforti ◽  
Aspartic Proteinases ◽  
Catalytic Rate Constant ◽  
Human Renin ◽  
Hydrolysis Of

The hexapeptide N-α-acetylalanylalanyl-lysyl-p- nitrophenylalanylalanylalanylamide has been synthesized and was found to be a good substrate for fungal aspartic proteinases that possess trypsinogen-activating activity, namely penicillopepsin, Rhizopus aspartic proteinase, Endothia aspartic proteinase and the aspartic proteinases from Aspergillus oryzae and Penicillium roqueforti. The peptide is rapidly cleaved between the lysine and p-nitrophenylalanine residues. Calf chymosin and human renin cleave the same bond, but only very slowly. The cleavage is accompanied by an absorbance decrease with a maximum at 296nm (Δε —1800m−1·cm−1). Pig pepsin and the aspartic proteinases from two Rhizomucor species cleave the peptide slowly on the carboxy side of p-nitrophenylalanine. For the five enzymes that hydrolysed the peptide rapidly, Km values range from 0.16 to 0.42mm and kcat. from 6 to 46.6s−1 at pH 4.5 and 25°C. A comparison of the kinetic parameters of the hexapeptide with those of the dipeptide N-α-acetyllysyl-p-nitrophenylalanylamide obtained with penicillopepsin shows that at pH 6.0 the catalytic rate constant kcat. is over 5000-fold greater for the hexapeptide, whereas the Km values are essentially the same, showing that the catalytic efficiency is strongly dependent on secondary binding. The new substrate with a p-nitrophenylalanine residue in the P′1 position has advantages over previously used substrates for aspartic proteinases in that it offers a more sensitive spectrophotometric assay that is independent of pH up to 5.5 and can readily be used up to pH 7.0. The presence of lysine makes it very water-soluble. Stopped-flow spectrophotometric experiments with penicillopepsin gave clear evidence that the hydrolysis of the substrate by penicillopepsin is not accompanied by a ‘burst’ release of p-nitrophenylalanylalanylalanylamide.

scholarly journals Substrate and inhibitor studies with human gastric aspartic proteinases

1990 ◽  
Vol 267 (3) ◽  
pp. 665-669 ◽  
Author(s):  
A Baxter ◽  
C J Campbell ◽  
C J Grinham ◽  
R M Keane ◽  
B C Lawton ◽  
...  
Keyword(s):  
Basement Membrane ◽  
Affinity Chromatography ◽  
Gastric Juice ◽  
Synthetic Peptide ◽  
Aspartic Proteinases ◽  
Peptide Substrates ◽  
Human Gastric Juice ◽  
Slow Moving ◽  
Hydrolysis Of ◽  
Chromatography Step

The separation of pepsin isoenzymes 1, 2, 3 and 5 (gastricsin) in human gastric juice was effected by chromatography on Mono Q ion-exchanger, and slow-moving proteinase was purified to homogeneity by using a modified procedure incorporating a novel affinity-chromatography step. The pH-activity profiles of these enzymes with mucus glycoprotein and basement-membrane substrates were determined; the profiles for pepsin 2 were noticeably different, and, in general, the pH optima for the hydrolysis of basement membrane were more acidic. Pepsin 1 expressed larger specificity constants (kcat./Km) than pepsin 3 with a series of synthetic peptide substrates, reflecting greater binding (smaller Km) by pepsin 1. Inhibitor studies at pH 1.7 and 4.5 with a series of P2-substituted lactoyl-pepstatins implied that valine at position P2 was optimal for inhibiting pepsins 1, 2 and 3 but detrimental for pepsin 5, whereas lysine at position P2 was tolerated well by pepsin 5 but not by pepsins 1, 2 and 3. The potency of lactoyl-pepstatin with lysine at position P2 did not increase as a function of pH. P2-substituted lactoyl-pepstatins failed to show any inhibitory selectivity among pepsins 1, 2 and 3.

Solid Dispersions: A Review

2014 ◽  
Vol 4 (2) ◽  
Author(s):  
Sumant Saini ◽  
Yashwant .
Keyword(s):  
Solid Dispersions ◽  
Physicochemical Characterization ◽  
Water Soluble ◽  
Absolute Minimum ◽  
Technology Transfers ◽  
Molecular Arrangement ◽  
Water Soluble Drugs ◽  
Carrier Solvent ◽  
Preparation Techniques ◽  
Selection Of

Solid dispersions are one of the most promising strategies to improve the oral bioavailability of poorly water soluble drugs. By reducing drug particle size to the absolute minimum, and hence improving drug wettability, bioavailability may be significantly improved. This article reviews the various preparation techniques for solid dispersion and compiles some of the recent technology transfers. The different types of solid dispersions based on the molecular arrangement have been highlighted. Some of the practical aspects to be considered for the preparation of solid dispersions, such as selection of carrier, solvent and methods of physicochemical characterization, along with an insight into the molecular arrangement of drugs in solid dispersions are also discussed. In this review, it is intended to discuss the recent advances related on the area of solid dispersions.

Peptide Inhibitors of Aspartic Proteinases with Hydroxyethylene Isostere Replacement of Peptide Bond. II. Preparation of Pseudotetrapeptides Derived from Diastereoisomeric 5-Amino-2-benzyl-4-hydroxy-6-phenylhexanoic Acids

1998 ◽  
Vol 63 (4) ◽  
pp. 541-548 ◽  
Author(s):  
Jaroslav Litera ◽  
Jan Weber ◽  
Ivana Křížová ◽  
Iva Pichová ◽  
Jan Konvalinka ◽  
...  
Keyword(s):  
Candida Albicans ◽  
Peptide Bond ◽  
Peptide Inhibitors ◽  
Aspartic Proteinases ◽  
Hiv 1

Twelve pseudotetrapeptides, Boc-NHCH(CH2Ph)CH(OH)CH2CH(CH2Ph) CO-Xaa-Phe-NH2 9-11, were prepared by [(benzotriazol-1-yl)oxy]tris(dimethylamino)phosphonium hexafluorophosphate-mediated couplings of diastereoisomeric O-silylated (2R or 2S,4R or 4S,5S)-2-benzyl-5-(tert-butoxycarbonyl)amino-4-hydroxy-6-phenylhexanoic acids 1 with dipeptides H-Xaa-Phe-NH2 (Xaa = Gln, Glu(OBzl) or Ile) 3-5, followed by O-deprotection. Pseudotetrapeptides 9-11 were tested for inhibition of aspartic proteinases secreted by Candida albicans and C. tropicalis. The level of inhibition of both yeast proteinases was very low, contrasting with the nanomolar IC50 values obtained for inhibition of HIV-1 proteinase.

scholarly journals Optimizing Chitin Depolymerization by Lysozyme to Long-Chain Oligosaccharides

Marine Drugs ◽  
2021 ◽  
Vol 19 (6) ◽  
pp. 320
Author(s):  
Arnaud Masselin ◽  
Antoine Rousseau ◽  
Stéphanie Pradeau ◽  
Laure Fort ◽  
Rodolphe Gueret ◽  
...  
Keyword(s):  
Time Course ◽  
Water Soluble ◽  
Organic Fertilizers ◽  
Symbiotic Associations ◽  
Egg White Lysozyme ◽  
Hen Egg White ◽  
Ecological Transition ◽  
Optimized Conditions ◽  
Hydrolysis Of ◽  
Long Chain

Chitin oligosaccharides (COs) hold high promise as organic fertilizers in the ongoing agro-ecological transition. Short- and long-chain COs can contribute to the establishment of symbiotic associations between plants and microorganisms, facilitating the uptake of soil nutrients by host plants. Long-chain COs trigger plant innate immunity. A fine investigation of these different signaling pathways requires improving the access to high-purity COs. Here, we used the response surface methodology to optimize the production of COs by enzymatic hydrolysis of water-soluble chitin (WSC) with hen egg-white lysozyme. The influence of WSC concentration, its acetylation degree, and the reaction time course were modelled using a Box–Behnken design. Under optimized conditions, water-soluble COs up to the nonasaccharide were formed in 51% yield and purified to homogeneity. This straightforward approach opens new avenues to determine the complex roles of COs in plants.

scholarly journals The Chemistry of Stress: Understanding the ‘Cry for Help’ of Plant Roots

Metabolites ◽  
2021 ◽  
Vol 11 (6) ◽  
pp. 357
Author(s):  
Muhammad Syamsu Rizaludin ◽  
Nejc Stopnisek ◽  
Jos M. Raaijmakers ◽  
Paolina Garbeva
Keyword(s):  
Root Exudate ◽  
Chemical Cues ◽  
Water Soluble ◽  
Plant Roots ◽  
Plant Tissues ◽  
Biotic And Abiotic Stresses ◽  
Primary And Secondary Metabolites ◽  
Cry For Help ◽  
Micro Organisms ◽  
Qualitative Changes

Plants are faced with various biotic and abiotic stresses during their life cycle. To withstand these stresses, plants have evolved adaptive strategies including the production of a wide array of primary and secondary metabolites. Some of these metabolites can have direct defensive effects, while others act as chemical cues attracting beneficial (micro)organisms for protection. Similar to aboveground plant tissues, plant roots also appear to have evolved “a cry for help” response upon exposure to stress, leading to the recruitment of beneficial microorganisms to help minimize the damage caused by the stress. Furthermore, emerging evidence indicates that microbial recruitment to the plant roots is, at least in part, mediated by quantitative and/or qualitative changes in root exudate composition. Both volatile and water-soluble compounds have been implicated as important signals for the recruitment and activation of beneficial root-associated microbes. Here we provide an overview of our current understanding of belowground chemical communication, particularly how stressed plants shape its protective root microbiome.

Biochemistry instructors’ use of intentions for student learning to evaluate and select external representations of protein translation

2019 ◽  
Vol 20 (4) ◽  
pp. 787-803
Author(s):  
Thomas J. Bussey ◽  
MaryKay Orgill
Keyword(s):  
Student Learning ◽  
Visual Cues ◽  
Bond Formation ◽  
Protein Translation ◽  
Peptide Bond ◽  
External Representation ◽  
External Representations ◽  
Peptide Bond Formation ◽  
Scientific Phenomena ◽  
Selection Of

Instructors draw on their intentions for student learning in the enactment of curriculum, particularly in the selection and presentation of external representation of scientific phenomena. These representations both create opportunities for students to experience non-experiential biochemical phenomena, such as protein translation, and constrain the possibilities for student learning based on the limited number of features depicted and the visual cues used to draw viewers attention to those features. In this study, we explore biochemistry instructors’ intentions for student learning about protein translation and how those intentions influence their selection of external representations for instruction. A series of instructor interviews were used to identify information that students need to know in order to develop a biochemically accurate understanding of protein translation. We refer to this information as the “critical features” of protein translation. Two dominant themes of critical features were identified: (1) components/structures of protein translation and (2) interactions/chemistry of protein translation. Three general components (the ribosome, the mRNA, and the tRNA) and two primary interactions (base pairing and peptide bond formation) were described by all instructors. Instructors tended to favor simpler, stylized representations that closely aligned with their stated critical features of translation for instructional purposes.

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