HPLC法测定仔猪小肠刷状缘膜囊孵育体系中的二肽含量

用高效液相色谱法测定了经仔猪小肠刷状缘膜囊水解后的甘 - L-脯、L-亮 -甘和 β-丙 -组共 3种二肽的剩余含量。分别以水 -三氟乙酸 (质量浓度分别为 0 .1 % ,0 .0 8%和 0 .1 % ,p H值分别为 2 .2 0 ,2 .30和 2 .2 0 )和乙腈 -三氟乙酸 (三氟乙酸质量浓度 0 .1 % )为流动相 ,经 Phenomennex ODS分析柱 (2 50 mm× 4.60 mm,5μm,C1 8)分离 ,在 2 0 0～ 40 0 nm处检测。结果表明 ,3种二肽在 0～ 30 0 μg.m L-1之间 ,其峰面积 (X)对质量浓度 (Y,μg.m L-1 )回归得方程分别为 Y=0 .0 0 0 1 X- 5.6945,(R2 =0 .9946) ;Y=0 .0 0 0 4 X- 1 .41 6 7,(R2 =0 .9999) ;Y=0 .1 842 X- 7.365 4,(R2 =0 .9948)。平均回收率依次为 1 0 0 .0 0 % ,1 0 0 .0 1 %和 99.92 % ,保留时间依次为 7.63,8.0 1和 4.1 7min,最大吸收波长依次为 2 0 1 ,2 0 0和 2 80 nm。该方法快速、简便和准确 ,结果稳定 ,重现性好 。

Structural, thermal and enzymatic analysis of naturally occurring and D-amino acid substituted peptides

Designing of new peptide materials for biomedical and protein engineering applications are important. In the present work an attempt has been made to study the effect of D-Leu in collagen like tetra peptide on the structure and stability of peptide against enzymes and results are compared with its chiral counterpart L-form. Effect of replacement of L-Leu in Leu-Gly-Pro-Ala tetra peptide with D-Leu on structure has been studied using circular dichroic spectroscopy (CD). Our findings suggest that, D-Leu substitution leads to conformational changes in Leu-Gly-Pro-Ala secondary structure from β-sheet to turns. L → D-Leu Configurational changes in Leu-Gly-Pro-Ala owes to enhanced thermal stability which has been substantiated through CD and differential scanning calorimetry. Change in chirality of the leucine inhibits collagenolytic activity, which enables to design selective inhibition of proteases with greater specificity.