Abstract:
:Trypsins have high sequence similarity, although the responses of insect trypsins to chemical and natural inhibitors suggest they differ in specificities. Purified digestive trypsins from insects of four different orders were assayed with internally quenched fluorescent oligopeptides with two different amino acids at P1 (Arg/Lys) and 15 amino acid replacements in positions P1', P2', P2, and P3. The binding energy (deltaG(s), calculated from Km values) and the activation energy (deltaG(T)(double dagger), determined from kcat/Km values) were calculated. Dictyoptera, Coleoptera and Diptera trypsins hydrolyze peptides with Arg at P1 at least 3 times more efficiently than peptides with Lys at P1, whereas Lepidoptera trypsins have no preference between Arg and Lys at that position. The hydrophobicities of each subsite were calculated from the efficiency of hydrolysis of the different amino acid replacements at that subsite. The results suggested that insect trypsin subsites become progressively more hydrophobic along evolution. Apparently, this is an adaptation to resist plant protein inhibitors, which usually have polar residues at their reactive sites. Results also suggested that, at least in lepidopteran trypsins, S3, S2, S1', and S2' significantly bind the substrate ground state, whereas in the transition state only S1' and S2' do that, supporting aspects of the presently accepted mechanism of trypsin catalysis. Homology modeling showed differences among those trypsins that may account for the varied kinetic properties.
journal_name
Insect Biochem Mol Bioljournal_title
Insect biochemistry and molecular biologyauthors
Lopes AR,Juliano MA,Marana SR,Juliano L,Terra WRdoi
10.1016/j.ibmb.2005.11.006subject
Has Abstractpub_date
2006-02-01 00:00:00pages
130-40issue
2eissn
0965-1748issn
1879-0240pii
S0965-1748(05)00212-2journal_volume
36pub_type
杂志文章abstract::Levels of mRNA for the two 3-hydroxy-3-methylglutaryl coenzyme A (HMG-CoA) synthases, (HMG-S1 and HMG-S2), and for HMG-CoA reductase (HMG-R) of Blattella germanica were analyzed in the fat body during the first gonadotrophic cycle. HMG-S2 and HMG-R showed the highest mRNA levels on day 0 and decreased thereafter, wher...
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journal_title:Insect biochemistry and molecular biology
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doi:10.1016/j.ibmb.2018.12.002
更新日期:2019-01-01 00:00:00
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journal_title:Insect biochemistry and molecular biology
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journal_title:Insect biochemistry and molecular biology
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更新日期:2009-07-01 00:00:00
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journal_title:Insect biochemistry and molecular biology
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journal_title:Insect biochemistry and molecular biology
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journal_title:Insect biochemistry and molecular biology
pub_type: 杂志文章
doi:10.1016/j.ibmb.2018.09.002
更新日期:2018-11-01 00:00:00
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journal_title:Insect biochemistry and molecular biology
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journal_title:Insect biochemistry and molecular biology
pub_type: 杂志文章
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abstract::Chagas disease or American trypanosomiasis, is a potentially life-threatening illness caused by the protozoan parasite, Trypanosoma cruzi. Once known as an endemic health problem of poor rural populations in Latin American countries, it has now spread worldwide. The parasite is transmitted by triatomine bugs, of which...
journal_title:Insect biochemistry and molecular biology
pub_type: 杂志文章
doi:10.1016/j.ibmb.2015.06.005
更新日期:2016-02-01 00:00:00
abstract::The recent literature on cytogenetic and molecular studies of Anopheles funestus, a major vector of malaria in Africa, is reviewed. Molecular data from West and Central Africa suggest a new species in the group closely allied to Anopheles rivulorum. Cytogenetic and molecular studies of populations from West, Central, ...
journal_title:Insect biochemistry and molecular biology
pub_type: 杂志文章,评审
doi:10.1016/j.ibmb.2004.03.012
更新日期:2004-07-01 00:00:00
abstract::The complete mitochondrial genome of the soybean aphid (Aphis glycines Matsumura), a major agricultural pest in the world, is described for the first time, which consists of 13 protein-coding genes, 22 tRNA genes, 2 rRNA genes, as well as a large repeat region between tRNA-Glu and tRNA-Phe, and an AT-rich control regi...
journal_title:Insect biochemistry and molecular biology
pub_type: 杂志文章
doi:10.1016/j.ibmb.2019.103208
更新日期:2019-10-01 00:00:00
abstract::The first full-length mRNA for vitellogenin (Vg) from ticks was sequenced. This also represents the first complete sequence of Vg from the Chelicerata and of a heme binding Vg. The Vg cDNA from the American dog tick, Dermacentor variabilis was 5744nt in length (GenBank Accession number AY885250), which coded for a pro...
journal_title:Insect biochemistry and molecular biology
pub_type: 杂志文章
doi:10.1016/j.ibmb.2007.01.004
更新日期:2007-04-01 00:00:00