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Journal Issue - Volume 6 Issue 11 (November 1997)

Abstract Cryptogein belongs to a new family of 10‐kDa proteins called elicitins. Elicitins are necrotic and signaling proteins secreted by Phytophthora spp. responsible for the incompatible reaction and systemic hypersensitive‐like necroses of diverse plant species leading to resistance against fungal or bacterial plant pathogens. The solution structure of β cryptogein from Phytophthoru cryptogea fungus was determined by using multidimensional...

Abstract The structure of pig pancreatic α‐amylase in complex with carbohydrate inhibitor and proteinaceous inhibitors is known but the successive events occurring at the catalytic center still remain to be elucidated. The X‐ray structure analysis of a crystal of pig pancreatic α‐amylase (PPA, EC 3.2.1.1.) soaked with an enzyme‐resistant substrate analogue, methyl 4,4′‐dithio‐α‐maltotrioside, showed electron density corresponding to...

Abstract The cellular protein, cyclophilin A (CypA), is incorporated into the virion of the type 1 human immunodeficiency virus (HIV‐1) via a direct interaction with the capsid domain of the viral Gag polyprotein. We demonstrate that the capsid sequence 87His‐Ala‐Gly‐Pro‐Ile‐Ala92 (87HAGPIA92) encompasses the primary cyclophilin A binding site and present an X‐ray crystal structure of the CypA/HAGPIA complex. In contrast to the cis prolines...

Abstract It is well established that sequence templates such as those in the PROSITE and PRINTS databases are powerful tools for predicting the biological function and tertiary structure for newly derived protein sequences. The number of X‐ray and NMR protein structures is increasing rapidly and it is apparent that a 3D equivalent of the sequence templates is needed. Here, we describe an algorithm called TESS that automatically...

Abstract Lipoprotein(a) [Lp(a)] is a low‐density lipoprotein complex consisting of apolipoprotein(a) [apo(a)] disulfide‐linked to apolipoprotein B‐100. Lp(a) has been implicated in atherogenesis and thrombosis through the lysine binding site (LBS) affinity of its kringle domains. We have examined the oxidative effect of 2,2′‐azobis‐(amidinopropane) HCI (AAPH), a mild hydrophilic free radical initiator, upon the ability of Lp(a) and...

Abstract Protein function is often controlled by ligand‐induced conformational transitions. Yet, in spite of the increasing number of three‐dimensional crystal structures of proteins in different conformations, not much is known about the driving forces of these transitions. As an initial step toward exploring the conformational and energetic landscape of protein kinases by computational methods, intramolecular energies and...

Abstract Green fluorescent protein (GFP) is autofluorescent. This property has made GFP useful in monitoring in vivo activities such as gene expression and protein localization. We find that GFP can be used in vitro to reveal and characterize protein‐protein interactions. The interaction between the S‐peptide and S‐protein fragments of ribonuclease A was chosen as a model system. GFP‐tagged S‐peptide was produced, and the...

Abstract Human extracellular superoxide dismutase (hEC‐SOD) is a secreted tetrameric protein involved in protection against oxygen free radicals. Because EC‐SOD is too large a protein for structural determination by multidimensional NMR, and attempts to crystallize the protein for X‐ray structural determination have failed, the three‐dimensional structure of hEC‐SOD is unknown. This means that alternative strategies for structural...

Abstract Two protein expression vectors have been designed for the preparation of NMR samples. The vectors encode the immunoglobulin‐binding domain of streptococcal protein G (GB1 domain) linked to the N‐terminus of the desired proteins. This fusion strategy takes advantage of the small size, stable fold, and high bacterial expression capability of the GB1 domain to allow direct NMR spectroscopic analysis of the fusion protein by...

Abstract Molecular models of Rous sarcoma virus (RSV) protease and 20 peptide substrates with single amino acid substitutions at positions from P4 to P3′, where the scissile bond is between P1 and Pl′, were built and compared with kinetic measurements. The unsubstituted peptide substrate, Pro‐Ala‐Val‐Ser‐Leu‐Ala‐Met‐Thr, represents the NC‐PR cleavage site of RSV protease. Models were built of two intermediates in the catalytic...

Abstract Essentially complete (96%) sequence‐specific assignments were made for the backbone and side‐chain 1H, 13C, and 15N resonances of Fusarium solani pisi cutinase, produced as a 214‐residue heterologous protein in Escherichia coli, using heteronuclear NMR techniques. Three structural features were noticed during the assignment. (1) The secondary structure in solution corresponds mostly with the structure from X‐ray diffraction, suggesting that both...

Abstract Calbindin D28k is an intracellular Ca2+‐binding protein containing six subdomains of EF‐hand type. The number and identity of the globular domains within this protein have been elucidated using six synthetic peptide fragments, each corresponding to one EF‐hand subdomain. All six peptides were mixed in equimolar amounts in the presence of 10 mM Ca2+ to allow for the reconstitution of domains. The mixture was compared to native calbindin...

Abstract Parvalbumins are a class of calcium‐binding proteins characterized by the presence of several helix‐loop‐helix (EF‐hand) motifs. It is suspected that these proteins evolved via intragene duplication from a single EF‐hand. Silver hake parvalbumin (SHPV) consists of three EF‐type helix‐loop‐helix regions, two of which have the ability to bind calcium. The three helix‐loop‐helix motifs are designated AB, CD, and EF,...

Abstract A computational study of the five soybean β‐amylase X‐ray structures reported so far revealed a peculiar conformational transition after substrate (or inhibitor) binding, which affects a segment of the β‐strand 6 (residues 341‐343) in the (β/α)8 molecular scaffold. Backbone distortions that involve considerable changes in the ø and ψ angles were observed, as well as two sharp rotamer transitions for the Thr342 and Cys343 side chains....

Abstract Mutations that suppress the defects introduced into T4 lysozyme by single amino acid substitutions were isolated and characterized. Among 53 primary sites surveyed, 8 yielded second‐site revertants; a total of 18 different mutants were obtained. Most of the restorative mutations exerted global effects, generally increasing lysozyme function in a number of primary mutant contexts. Six of them were more specific, suppressing...

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