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New analogues of Cucurbita maxima trypsin inhibitor III (CMTI III) with simplified structure.

Seven new analogues of trypsin inhibitor CMTI III were obtained by solid-phase peptide synthesis. Three analogues contained only two, instead of three, disulfide bridges, whereas the molecules of the next four analogues were shortened at the N- and/or C-terminus. The elimination of one disulfide bridge in CMTI III induces a decrease in the association equilibrium constants by 6-7 orders of magnitude, whereas the removal of one, two or three amino-acid residues at the N- and/or C-terminus does not significantly affect the activity.

Amino Acid Sequence↗

Glycine-rich analogues of Cucurbita maxima trypsin inhibitor (CMTI-III) substituted by valine in position 27 display relatively low antitrypsin activity.

Five new analogues of the trypsin inhibitor CMTI-III were synthesized by the solid-phase method. All analogues containing a valine residue in position 27 and glycine residues in some or all of the positions 9, 11, 14, 17, 19, 29 as well as in two cases a norleucine residue in position 8 displayed association equilibrium constants by 6-7 orders of magnitude lower than the native CMTI-III inhibitor.

Amino Acid Sequence↗

New active analogues of Cucurbita maxima trypsin inhibitor III (CMTI-III) modified in the non-contact region.

Four new analogues of trypsin inhibitor CMTI-III(3-28) = [desArg1,desVal2,desGly29]CMTI-III which was recently shown to be fully active, were synthesized by the solid-phase method. The introduction of glycine in position 9 (peptide 1) and Gly-Pro-Gly (peptide 2) and Gly-Pro-Asn (peptide 3) in the regions 17-19 and 23-25, respectively, did not change the antitrypsin activity of all modified peptides. All of these substitutions are presumed to be outside the trypsin-binding loop as judged from the X-ray structure of the complex between beta-trypsin and the related inhibitor CMTI-I. Also the fourth analogue which was substituted in all the positions mentioned, exhibited the full activity.

Amino Acid Sequence↗

Analogues of Cucurbita maxima trypsin inhibitor III (CMTI-III) with elastase inhibitory activity.

Three new CMTI-III analogues containing the Val residue in the reactive site (position 5) were synthesized by the solid-phase method. The analogues displayed an elastase inhibitory activity. It is shown that the removal of the N-terminal Arg residue and the introduction of the Gly-Pro-Gln tripeptide in the region 23-25 decreases the antielastase activity by two orders of magnitude. The removal of the disulfide bridge in positions 16-28 and the substitution of Ala for Cys16 and Gly for Cys28 decreases the activity (measured as Ka with HLE) by five orders of magnitude as compared with [Val5]CMTI-III.

Amino Acid Sequence↗

[Chemical and biological characterization of meal and protein isolates from pumpkin seed (Cucurbita moschata)].

The present study was carried out in order to check through chemical and biological analyses the nutritional characteristics of pumpkin seed, its delipidized meal and its proteic concentrate, considering its availability, nutritional potential, facility for production in poor soils and the need for new food resources. Another objective was to complement the amino acid pattern of pumpkin with others protein sources for human consumption. The results obtained indicate that: Raw pumpkin seed meal has a proteic values of 37.6% and the delipidized meal 68.8%; The PER values for raw seed meal and delipidized meal were 2.26 and 1.65, respectively; The chemical composition revealed that the delipized pumpkin seed meal was limited in threonine (66.8%); The isolate and seed meal proteins were both complemented with lysine and with cowpea bean meal; Whole pumpkin seed meal obtained from variety Caravelle is a good caloric material (approximately 568 cal/100 g).

Amino Acids↗

The influence of plant growth regulators on callus induction in pumpkin (Cucurbita pepo L.) hairy roots.

Following in vitro infection with Agrobacterium rhizogenes wild strain (mannopine, 8196) and two A. tumefaciens transconjugant strains (C58C1 pArA4abc and C58C1 pArA4b) transformed (hairy) roots were induced in pumpkin (C. pepo L.) cotyledons. The presence of pRi T-DNA in pumpkin long-term hairy root cultures was determined by Southern hybridization. The influence of plant growth regulators on callus induction in root explants from hairy root lines, which differed mutually in morphology and growth rate, was tested by the addition of growth regulators to basal nutrient medium; while 2.4-D inhibited root proliferation in all hairy root lines tested, callus induction depended both on plant growth regulators and the root line.

Cell Differentiation↗

[Mycotoxins of Fusarium spp. in rotten fruits from Cucurbita ficifolia].

Swine acute toxicosis with hemorrhages was recognized after feeding on decayed chayotes (C. ficifolia fruits). In order to elucidate the origin of this pathology, chayotes spoiled by fusaria were analyzed. The mycotoxins (T-2 toxin, fusarenon X) identified in decayed chayotes, the mice alterations and the isolated species (F. equiseli, F. graminearum, F. heterosporum, F. sambucinum var. coeruleum and F. solani), suggest that the effects on swine may be due to trichothecenes produced by fusaria within fruits, and that eating damaged chayotes is dangerous for animals.

Food Contamination↗

[Obtention and evaluation of a precooked flour of auyama (Cucurbita maxima) and rice, enriched with oleaginous proteins and/or skim milk].

The purpose of the present study was the production of a precooked blend made of pumpkin squash and rice flour (PRB), processed with drum dyer. The blend was supplemented with different protein sources: soy, sesame and deffated milk. The following formulations were obtained: I) PRB + 10.5% deffated soy flour; II) PRB + 15% deffated milk; III) PRB + 5% deffated sesame flour + 10% deffated milk; IV) PRB + 5% deffated soy flour + 10% deffated sesame flour, and V) PRB + 9.5% deffated soy flour + 9.5% deffated milk. All formulations were submitted to physico-chemical, nutritional and sensorial evaluation. The protein content of the formulations varied from 14.6% to 17.9%. Rat assays gave satisfactory net protein ratio values. Soups prepared with the formulations were qualified as having good organoleptic characteristics. The production of some of the formulations described above, would contribute to a larger utilization of pumpkin, as it would allow the easy preparation of salted and sweet dishes (soups, cakes, etc).

Amino Acids↗

The serine proteinase inhibitor from summer squash (Cucurbita pepo): some structural features, stability and proteolytic degradation.

The serine proteinase inhibitor from summer squash seeds (CPTI-II) with Mr of about 3250 contains three disulphide bridges and is unusually resistant to denaturing agents (e.g. 10% trichloroacetic acid at about 100 degrees C), thermolysin and proteinase V8 from Staphylococcus aureus. The inhibitor is digested by pepsin; the digestion of the virgin form proceeds more rapidly than when the peptide bond of the reactive site is broken. The inhibitor is not specifically reduced by sodium borohydride at pH 8.8, and almost full reactivation of the inhibitor reduced by dithiothreitol takes place at pH 8.15 in the presence of EDTA and the reduced + oxidized glutathione system. The inhibitor was crystallized from methanol. CD spectra point to the occurrence of beta-turns in the secondary structure of the inhibitor.

Circular Dichroism↗

Isolation of two trypsin inhibitors from resting seeds of the white bush (Cucurbita pepo var. patissonina) and their properties.

Two trypsin inhibitors, CPPTI-I and CPPTI-II of Mr 3 250 and 7 850, respectively, were isolated from resting white bush seeds. Both inhibitors are cysteine-rich proteins. In addition to trypsin, they inhibit a trypsin-like enzyme isolated from Streptomyces griseus proteinase but they do not act on chymotrypsin, kallikrein or subtilopeptidase A. The isolated inhibitors contain a lysine residue in position P1 of the reactive site.

Amino Acids↗