No description available.

Bipyramidal crystalline, spheroidal crystalline and amorphous proteins were prepared from following four seeds: white kidney, navy (Phaseolus vulgaris) beans; baby lima, large lima (Phaseolus lunatus) beans. A study of the biological properties of the proteins which exhibit the different microstructures, was carried out. The nature of tryptic inhibitory activity and alpha-amylase inhibitory activity were investigated. All protein showed both trypsin inhibitory and alpha-amylase activities; the kinetics of the alpha-amylase revealed non-competitive mechanism. The crystalline isolates showed lower trypsin inhibitory (TI) and alpha-amylase inhibitory (AI) activities than the amorphous isolates. The extents of tryptic hydrolysis (in vitro) were not related to TI indicating involvement of some other factors, in addition to trypsin inhibitory activity. Electropherograms of SDS-PAGE indicated that the major proteins of P. lunatus beans were more resistant to tryptic hydrolysis than the major fractions of the P. vulgaris. Phytate was found to have an effect on trypsin inhibition as well as on alpha-amylase inhibition; in the latter case, however, phytate complexed to protein was required for the inhibitory effect. There were no relationships between tannin content of the proteins and biological activity. Fractionation of bipyramidal crystalline and amorphous proteins by size exclusion chromatography showed that each isolate contained three fractions having approximate MW of 443,000, 200,000 and 150,000 daltons. The 200,000 MW fraction was a principal fraction. The fraction of 150,000 contained most of the trypsin inhibitory activity, alpha-amylase inhibitory activity was not detected in any of the fractions.

This study was directed at elucidating the structural and functional characteristics of legume protein isolates with different microstructures. / Protein isolates with different microstructures (crystalline and amorphous) were prepared from four varieties of Phaseolus beans; white kidney bean and navy bean (P. vulgaris), and large lima and baby lima beans (P. lunatus). The protein isolates were subjected to tryptic hydrolysis at various time intervals, and the effect of hydrolysis on the functional properties of the protein isolates was studied, using bovine casein as control. Reversed phase HPLC with UV detection was used to generate peptide maps of the tryptic hydrolysates, and electrospray mass spectrometry was used to characterize the peptide profile of the protein hydrolysates. / There was no difference between the susceptibility of the crystalline and amorphous protein isolates to tryptic hydrolysis, however, the hydrolytic products of the crystalline isolates showed higher solubility and functional properties compared with those of the amorphous isolates. Limited hydrolysis markedly improved the functional properties of both crystalline and amorphous protein isolates. The effect of hydrolysis on the functionality of the bean protein isolates was higher compared with casein. In general the hydrolysates of the bean protein isolates showed higher functional properties than casein and its hydrolysates. / Reversed phase HPLC peptide mapping of the tryptic digests and ESI/MS of the RP-HPLC fractions showed structural and compositional difference between crystalline and amorphous protein isolates prepared from the same bean variety. The results also showed that off-line ESI/MS, and ESI/MS/MS of RP-HPLC fractions of the tryptic hydrolysates could be used for the structural characterization of the protein isolates.

No description available.

No description available.

published_or_final_version / Botany / Doctoral / Doctor of Philosophy

Whole safflower seeds of the Mexican variety Kino'76 with a protein content of 17.30% (dwb) were subjected to the processes of dehulling, defatting (n-hexane extraction) and debittering (70% methanol extraction) to produce four types of meals preparations: whole safflower meal, dehulled safflower meal, debittered, whole meal and debittered, dehulled meal with protein contents of 26.90, 66.93, 26.70 and 69.92%, respectively. The proteins of each meal were studied in detail by means of protein fractionation, gel filtration chromatography and sodium dodecyl sulfate-polyacrylamide gel electrophoresis (SDS-PAGE). Osborne solubility fractionation of the protein of whole safflower meal showed that the amount of protein in the alkali soluble fraction was approximately 71% of the total and the alcohol soluble fraction did not contain any protein. After dehulling and debittering, the amount of protein in the alkali soluble fraction decreased by 30%, whereas the amount of protein in the insoluble residue increased by 12%. SDS-PAGE of the proteins of the water-, salt- and alkali soluble fractions revealed that they consisted of 8, 13 and 13 distinct subunits, respectively, with apparent molecular weights ranging from 14.7 to 88.0 kDa. The number of subunits and molecular weight distribution decreased as a result of debittering. Fractionation of the proteins of each meal by gel filtration chromatography followed by SDS-PAGE demonstrated that proteins of safflower seed are highly heterogeneous. The process of debittering caused major alteration of the molecular weight profile and subunit composition of the gel filtration protein fractions.

published_or_final_version / Chemistry / Master / Master of Philosophy

This work was devoted to the study of (a) the physico-chemical, functional, and structural properties of bean (Phaseolus sp.) protein isolates in relation to their microstructures, and (b) the effects of protein carbohydrate interactions on physico-chemical, functional, and structural properties. The contents of protein, and both total and individual sugars of alkali extracted (amorphous) and citric acid extracted (bipyramidal and spheroidal) proteins from Phaseolus vulgaris (white kidney and navy) and Phaseolus lutanus (baby lima and large lima) beans were determined. The proteins were subjected to differential scanning calorimetry, and measurements of surface tension (air-water interface), surface hydrophobicity, and foam expansion. Structural analysis of the proteins were performed using Fourier transform infrared (FT-IR) spectroscopy. Enzymatic and chemical deglycosylation was performed on a white kidney bean protein isolate. / Glucose and mannose were the major sugars found in the isolates. Bipyramidal and spheroidal microstructures with higher protein contents generally had greater mannose content and lower glucose content. Differences in enthalpy of denaturation $( Delta$H), surface tension decay curves, surface hydrophobicities, and foam expansions were observed with isolates of different microstructures. Corresponding differences in molecular structure were not, however, detected by FT-IR spectroscopy. Using statistical analysis, a relationship between foam expansion and the $ Delta$H, solubility, surface hydrophobicity and surface tension of the isolates was obtained. Preliminary results suggest that the removal of carbohydrate influenced the physico-chemical properties of the protein.

Centrifugation of coconut milk resulted in cream, skim milk, and insoluble solids. Proteins were isolated from skim milk by the addition of acid, with or without heating. The separation and isolation gave the following coconut protein preparations: coconut milk, coconut skim milk, insoluble solids, acid precipitate, and acid-heat precipitate. / Trypsin inhibitory activity (TIA) of the coconut protein preparations was relatively low while tryptic digestibility of the isolated proteins was considerably lower than those of the coconut milk and skim milk, the digestibility of coconut protein preparations was lower than that of casein. In general, the emulsifying and farming properties of coconut protein preparations were lower than casein. The insoluble solids showed the highest viscosity when compared with the coconut protein preparations. In contrast to the whey protein concentrate (WPC), the apparent strain of gels from the acid precipitate increased as the pH increased. The gelation properties at pH 3 of the insoluble solids were better than WPC. / The estimated molecular weight by size-exclusion chromatography of coconut protein preparations gave 3 fractions with MW ranging from 6850 Da to 229402 Da. In native PAGE, coconut proteins were separated into at least 3 subunits and under SDS-denatured conditions, the major protein subunits showed MW of 54531 Da and 25008 Da, respectively. RP-HPLC separation of coconut milk, acid precipitate, and acid-heat precipitate gave 3 fractions containing several species of MW ranging between 35574 Da to 51209 Da when analyzed by mass spectometry.