| The crude tuberin was extracted from the Netherlands potato by Osborne method, optimization its extraction craft by single factor experiment. The results showed that when the dosage liquor ratio is 1:12, temperature is 35℃, diffusion time is 1h, the concentration of NaCl is lmol/L, extracted twice, the extraction ratio was 85%.Take semimicro Kjeldah method and isoelectric focusing technology determined the protein level and isoelectric points of crude tuberin, the results showed that the protein level is 96.7% and it exists 3 isoelectric points, dicern as 5.83,6.0.6.7.Tuberin is one of third main storage protein in potato, most distribution in its tubers, holds 25% of all potato protein. It is a kind of salting protein, contains higher essential amino acid of Leucine, Lysine and Valine, and the essential amino acid higher obviously than the recommendation value of FAO/WHO. Therefore, it is a good kind of protein source to food processing.The crude tuberin was purified by Sephadex G-50 and DEAE-Cellulose 52 anion. The results showed that the max absorption peak of 280nm, and the molecular weight was 22-KD, when the concentration of salt is 0.67mol/L. These results will provide help for the relationship between the structure and function of tuberin.The purified 22-KD tuberin for structural analysis of amino acid analysis, X-powder diffraction pattern, circular dichroism analysis and IR analysis, the results showed that the essential amino acids of valine, leucine, lysine Higher levels, respectively is 5.69 g/100g,5.54 g/100g,5.51 g/100g, but methionine, cystine content is very low, namely 0.92 g/100g,0.61 g/100g, this indicated that the sulfur-containing amino acids is the limiting amino acid in 22-KD tuberin; 22-KD tuberin secondary structure is mainly unordered, accounting for more than 85%,βsheet and a helix content close,βturns is the lowest. |
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