scholarly journals Critical role of amino acid 23 in mediating activity and specificity of vinckepain-2, a papain-family cysteine protease of rodent malaria parasites

2002 ◽  
Vol 368 (1) ◽  
pp. 273-281 ◽  
Author(s):  
Ajay SINGH ◽  
Bhaskar R. SHENAI ◽  
Youngchool CHOE ◽  
Jiri GUT ◽  
Puran S. SIJWALI ◽  
...  
Keyword(s):  
Amino Acid ◽  
Drug Discovery ◽  
Drug Targets ◽  
Critical Role ◽  
Cysteine Proteases ◽  
Malaria Parasites ◽  
Ph Optimum ◽  
Peptide Substrates ◽  
Rodent Malaria

Cysteine proteases of Plasmodium falciparum, known as falcipains, have been identified as haemoglobinases and potential drug targets. As anti-malarial drug discovery requires the analysis of non-primate malaria, genes encoding related cysteine proteases of the rodent malaria parasites P. vinckei (vinckepain-2) and P. berghei (berghepain-2) were characterized. These genes encoded fairly typical papain-family proteases, but they contained an unusual substitution of Gly23 with Ala (papain numbering system). Vinckepain-2 was expressed in Escherichia coli, solubilized, refolded and autoprocessed to an active enzyme. The protease shared important features with the falcipains, including an acidic pH optimum, preference for reducing conditions, optimal cleavage of peptide substrates with P2 Leu and ready hydrolysis of haemoglobin. However, key differences between the plasmodial proteases were identified. In particular, vinckepain-2 showed very different kinetics against many substrates and an unusual preference for peptide substrates with P1 Gly. Replacement of Ala23 with Gly remarkably altered vinckepain-2, including loss of the P1 Gly substrate preference, markedly increased catalytic activity (kcat/Km increased approx. 100-fold) and more rapid autohydrolysis. The present study identifies key animal-model parasite targets. It indicates that drug discovery studies must take into account important differences between plasmodial proteases and sheds light on the critical role of amino acid 23 in catalysis by papain-family proteases.

scholarly journals Mining the Information for Structure Based Drug Designing by Relational Database Management Notion

2009 ◽  
Vol 6 (4) ◽  
pp. 1047-1054
Author(s):  
R. Balajee ◽  
M. S. Dhanarajan
Keyword(s):  
Drug Discovery ◽  
Drug Targets ◽  
Three Dimensional ◽  
Chemical Properties ◽  
Structure Based Drug Design ◽  
Molecular Systems ◽  
Drug Discovery Program ◽  
And Behavior

Structure based drug design is a technique that is used in the initial stages of a drug discovery program. The role of various computational methods in the characterization of the chemical properties and behavior of molecular systems is discussed. The field of bioinformatics has become a major part of the drug discovery pipeline playing a key role for validating drug targets. By integrating data from many inter-related yet heterogeneous resources, informatics can help in our understanding of complex biological processes and help improve drug discovery. The determination of the three dimensional properties of small molecules and macromolecular receptor structures is a core activity in the efforts towards a better understanding of structure-activity relationships.

scholarly journals Critical role of ASCT2-mediated amino acid metabolism in promoting leukaemia development and progression

2019 ◽  
Vol 1 (3) ◽  
pp. 390-403 ◽  
Author(s):  
Fang Ni ◽  
Wen-Mei Yu ◽  
Zhiguo Li ◽  
Douglas K. Graham ◽  
Lingtao Jin ◽  
...  
Keyword(s):  
Amino Acid ◽  
Amino Acid Metabolism ◽  
Acid Metabolism ◽  
Critical Role

Critical Role of Dipeptidyl Peptidase IV: A Therapeutic Target for Diabetes and Cancer

2018 ◽  
Vol 19 (2) ◽  
pp. 88-97 ◽  
Author(s):  
Sourav De ◽  
Subhasis Banerjee ◽  
S.K. Ashok Kumar ◽  
Priyankar Paira
Keyword(s):  
Drug Targets ◽  
Critical Role ◽  
Dipeptidyl Peptidase ◽  
Dipeptidyl Peptidase Iv ◽  
Dpp Iv ◽  
Protease Enzyme ◽  
Target Disease ◽  
Dimeric Form ◽  
Epithelium Cells

Diabetes mellitus is an emerging predator and affecting around 422 million adults worldwide. Higher levels of circulating insulin and increased pressure on the pancreas to produce insulin have been inferred as possible etiology for diabetes leading to a higher risk of pancreatic cancer. Out of several drug targets in hypoglycemic discovery, Dipeptidyl peptidase-IV (DPP-IV) has been considered an emerging target. It is a protease enzyme which inactivates incretin hormones i.e., Glucagonlike peptide 1 (GLP-1) and glucose-dependent insulin tropic polypeptide (GIP). Inhibition of DPP-4 results in the longer action of GLP-1 and GIP, therefore, DPP-4 inhibitors play an important role in maintaining glucose homeostasis. In comparison to early oral hypoglycemic, DPP-IV inhibitors are well tolerated and provide a better glycemic control over a longer period. These enzymes are expressed in a dimeric form on the surface of different cells such as prostate, liver and small intestinal epithelium cells. Disruption of the local signaling environment is an emerging factor in cancer development. Till date, not even a single DPP-IV inhibitor as anticancer has been developed. This review focuses on various features of the enzyme and their suitable inhibitors for target disease.

scholarly journals Critical role of amino acid position 343 of surfactant protein-D in the selective binding of glycolipids from Mycobacterium tuberculosis

Glycobiology ◽  
2009 ◽  
Vol 19 (12) ◽  
pp. 1473-1484 ◽  
Author(s):  
Tracy K Carlson ◽  
Jordi B Torrelles ◽  
Kelly Smith ◽  
Tim Horlacher ◽  
Riccardo Castelli ◽  
...  
Keyword(s):  
Mycobacterium Tuberculosis ◽  
Amino Acid ◽  
Critical Role ◽  
Amino Acid Position ◽  
Surfactant Protein ◽  
Surfactant Protein D ◽  
Selective Binding

scholarly journals Characterization of a Thermoacidophilic l-Arabinose Isomerase from Alicyclobacillus acidocaldarius: Role of Lys-269 in pH Optimum

2005 ◽  
Vol 71 (12) ◽  
pp. 7888-7896 ◽  
Author(s):  
Sang-Jae Lee ◽  
Dong-Woo Lee ◽  
Eun-Ah Choe ◽  
Young-Ho Hong ◽  
Seong-Bo Kim ◽  
...  
Keyword(s):  
Amino Acid ◽  
Amino Acid Sequences ◽  
Site Directed Mutagenesis ◽  
Bacillus Halodurans ◽  
Wild Type ◽  
Ph Optimum ◽  
Calculated Molecular Mass ◽  
Alicyclobacillus Acidocaldarius ◽  
Arabinose Isomerase

ABSTRACT The araA gene encoding l-arabinose isomerase (AI) from the thermoacidophilic bacterium Alicyclobacillus acidocaldarius was cloned, sequenced, and expressed in Escherichia coli. Analysis of the sequence revealed that the open reading frame of the araA gene consists of 1,491 bp that encodes a protein of 497 amino acid residues with a calculated molecular mass of 56,043 Da. Comparison of the deduced amino acid sequence of A. acidocaldarius AI (AAAI) with other AIs demonstrated that AAAI has 97% and 66% identities (99% and 83% similarities) to Geobacillus stearothermophilus AI (GSAI) and Bacillus halodurans AI (BHAI), respectively. The recombinant AAAI was purified to homogeneity by heat treatment, ion-exchange chromatography, and gel filtration. The purified enzyme showed maximal activity at pH 6.0 to 6.5 and 65°C under the assay conditions used, and it required divalent cations such as Mn2+, Co2+, and Mg2+ for its activity. The isoelectric point (pI) of the enzyme was about 5.0 (calculated pI of 5.5). The apparent Km values of the recombinant AAAI for l-arabinose and d-galactose were 48.0 mM (V max, 35.5 U/mg) and 129 mM (V max, 7.5 U/mg), respectively, at pH 6 and 65°C. Interestingly, although the biochemical properties of AAAI are quite similar to those of GSAI and BHAI, the three AIs from A. acidocaldarius (pH 6), G. stearothermophilus (pH 7), and B. halodurans (pH 8) exhibited different pH activity profiles. Based on alignment of the amino acid sequences of these homologous AIs, we propose that the Lys-269 residue of AAAI may be responsible for the ability of the enzyme to act at low pH. To verify the role of Lys-269, we prepared the mutants AAAI-K269E and BHAI-E268K by site-directed mutagenesis and compared their kinetic parameters with those of wild-type AIs at various pHs. The pH optima of both AAAI-K269E and BHAI-E268K were rendered by 1.0 units (pH 6 to 7 and 8 to 7, respectively) compared to the wild-type enzymes. In addition, the catalytic efficiency (k cat/Km ) of each mutant at different pHs was significantly affected by an increase or decrease in V max. From these results, we propose that the position corresponding to the Lys-269 residue of AAAI could play an important role in the determination of the pH optima of homologous AIs.

scholarly journals Insights into the mysterious genetic variation profile oftprKinTreponema pallidumunder the development of natural human syphilis infection

2019 ◽  
Author(s):  
Dan Liu ◽  
Man-Li Tong ◽  
Yong Lin ◽  
Li-Li Liu ◽  
Li-Rong Lin ◽  
...  
Keyword(s):  
Amino Acid ◽  
Immune Evasion ◽  
High Frequency ◽  
Critical Role ◽  
Treponema Pallidum ◽  
Secondary Syphilis ◽  
Human Infection ◽  
Amino Acid Sequences ◽  
Potential Vaccine

AbstractAlthough the variations of thetprKgene inTreponema pallidumwere considered to play a critical role in the pathogenesis of syphilis, how actual variable characteristics oftprKin the course of natural human infection enabling the pathogen’s survive has thus far remained unclear. Here, we performed NGS to investigatetprKofT. pallidumdirectly from primary and secondary syphilis samples. Compared with diversity intprKof the strains from primary syphilis samples, there were more mixture variants found within seven V regions of thetprKgene among the strains from secondary syphilis samples, and the frequencies of predominant sequences within V regions oftprKwere generally decreased (less than 80%) with the proportion of minor variants in 10-60% increasing. Noteworthy, the variations within V regions oftprKalways obeyed a strict 3 bp changing pattern. AndtprKin the strains from the two-stage samples kept some stable amino acid sequences within V regions. Particularly, the amino acid sequences IASDGGAIKH and IASEDGSAGNLKH in V1 not only presented a high proportion of inter-population sharing, but also presented a relatively high frequency (above 80%) in the populations. Besides,tprKalways demonstrated remarkable variability in V6 at both the intra- and inter-strain levels regardless of the course. These findings unveiled that the different profile oftprK in T. pallidumdirectly from primary and secondary syphilis samples, indicating that throughout the development of syphilisT. pallidumconstantly varies its domaintprKgene to obtain the best adaptation to the host. While this changing was always subjected a strict gene conversion mechanism to keep an abnormal TprK. The highly stable peptides found in V1 would probably be promising potential vaccine components. And the highly heterogenetic regions (e.g. V6) could provide insight into the mysterious role oftprKin immune evasion.Author summaryAlthough the variations of thetprKgene inTreponema pallidumwere considered to play a critical role in the pathogenesis of syphilis, how actual variable characteristics oftprKin the course of natural human infection enabling the pathogen’s survive has thus far remained unclear. Here, we performed next-generation sequencing, a more sensitive and reliable approach, to investigatetprKofTreponema pallidumdirectly from primary and secondary syphilis patients, revealing that the profile oftprKinT. pallidumfrom the two-stage samples was different. Within the strains from secondary syphilis patients, more mixture variants within seven V regions oftprKwere found, the frequencies of their predominant sequences were generally decreased with the proportion of minor variants in 10-60% was increased. And the variations within V regions oftprKalways obeyed a strict 3 bp changing pattern. Noteworthy, the amino acid sequences IASDGGAIKH and IASEDGSAGNLKH in V1 presented a high proportion of inter-population sharing and presented a relatively high frequency in the populations. And V6 region always demonstrated remarkable variability at intra- and inter-patient levels regardless of the course. These findings provide insights into the mysterious role of TprK in immune evasion and for further exploring the potential vaccine components.

scholarly journals Identification of the amino acid residue responsible for the myricetin sensitivity of human proton-coupled folate transporter

2019 ◽  
Vol 9 (1) ◽  
Author(s):  
Takahiro Yamashiro ◽  
Tomoya Yasujima ◽  
Kinya Ohta ◽  
Katsuhisa Inoue ◽  
Hiroaki Yuasa
Keyword(s):  
Amino Acid ◽  
Amino Acid Residue ◽  
Potential Risk ◽  
Critical Role ◽  
Initial Analysis

AbstractHuman proton-coupled folate transporter (hPCFT/SLC46A1) has recently been found to be inhibited by myricetin by a sustained mechanism, raising a concern that the inhibition might lead to malabsorption of folates in the intestine, where hPCFT works for their epithelial uptake. However, rat PCFT (rPCFT) has more recently been found not to be inhibited by myricetin. Prompted by this finding, we attempted to determine the amino acid residue involved in that by analyses comparing between hPCFT and rPCFT. In the initial analysis, chimeric constructs prepared from hPCFT and rPCFT were examined for myricetin sensitivity to determine the hPCFT segment involved in the sensitivity. Focusing on the thereby determined segment from 83rd to 186th amino acid residue, hPCFT mutants having a designated amino acid residue replaced with its counterpart in rPCFT were prepared for the subsequent analysis. Among them, only G158N-substituted hPCFT was found to be transformed to be insensitive to myricetin and, accordingly, oppositely N158G-substituted rPCFT was transformed to be sensitive to myricetin. These results indicate the critical role of Gly158 in the myricetin sensitivity of hPCFT. This finding would help advance the elucidation of the mechanism of the myricetin-induced inhibition of hPCFT and manage the potential risk arising from that.

Sign in / Sign up

Export Citation Format

Share Document