Sorghum seed is traditionally used as secondary food sources in addition to rice in Korea. While the hypoglycemia regulating phytochemicals have been found in sorghum seed, peptides related with hypoglycemia never been studied before. To obtain the peptide characteristics and the specifically high-expressed peptides in hypoglycemic sorghum seed, peptide profiles of seven hypoglycemic and five nonhypoglycemic sorghum lines bred in RDA were determined using surface-enhanced laser desorption/ionization time-offlight mass spectrometry (SELDI-TOF MS). The twelve sorghum lines exhibited 104 peptides on CM10 protein chip array (weak cation exchange) and 95 peptides on Q10 (weak cation exchange) in the molecular mass range from 2,000 to 20,000 Da. Heat map via supervised hierarchical clustering of the significantly different peptides (p < 0.01) in peak intensity among the 12 lines effectively revealed the specifically upregulated peptides in each line and distinguished between 7 hypoglycemic and 5 non-hypoglycemic lines. Through the comparison with hypoglycemic and non-hypoglycemic lines, 10 peptides including 2231.6, 2845.4, 2907.9, 3063.5, 3132.6, 3520.8, 4078.8, 5066.2, 5296.5, 5375.5 Da were specifically high-expressed in hypoglycemic lines at p < 0.00001. This study characterized seed peptides of 12 sorghums and found ten peptides highly expressed for hypoglycemic sorghum lines, which could be used as peptide biomarkers for identification of hypoglycemic sorghum.

Sorghum seed is traditionally used as health supplements and the secondary food mixed with rice in Korea. While the research of reserve protein in sorghum seed have been carried out in many countries used as major food, much less is known about reserve proteins of Korean local sorghum seeds. To obtain protein characteristics in 20 Korean local sorghum seed, quantitative content of reserve protein was determined after fractionation by modified ‘Osbone’ method and α-kafirin of prolamin was determined by SDSPAGE. Mean albumin, globulin, prolamin and glutelin contents based on total seed protein content of 20 Korean local sorghum seed were 6.2%, 0.9%, 57.9% and 35.1%, respectively. Sorghum cultivar with high prolamin were ‘Whin-susu’, ‘Whin-Chalsusu’, ‘Whanggeum-Chalsusu’, and ‘Daepungshushu’. Sorghum cultivar with high α-kafirin were ‘Whin-susu’, ‘Geumsan-Chalsusu’, ‘Whin-Chalsusu’, and ‘Jangmok-susu’. Among the 20 varieties, ‘Whin-susu’ and ‘Whin-Chalsusu’ were selected as high α -kafirin and prolamin sorghum cultivar, which showed 64.5 and 71.9% of prolamin contents, respectively.

SELDI-TOF MS를 활용한 저분자 펩타이드 분석을 위해 서는 분석시료에 대한 최적화 분석조건을 확립하는 것이 필수적으로 선행되어야 한다. 본 연구는 수수 종자 내 존재하는 10 kDa 이하의 저분자 펩타이드를 프로파일링하기 위하여 활용된 SELDI-TOF MS의 최적화 분석조건을 확립하는데 있다. 분석조건은 (1) 프로테인 칩: CM10(weak cationexchanger), Q10(strong anion exchanger), (2) 바인딩 버퍼의 희석배수: 1/2, 1/5, 1/10, 1/20, 1/50, 1/100, 1/200, (3)Q10의 바인딩 버퍼 강도: 10 mM, 100 mM, (4) 단백질 추출버퍼: sodium borate, sodium borate + acetone, phenol,TCA 버퍼로 하였다.1. 바인딩 버퍼의 희석배수는 CM10과 Q10 모두 1/20과1/50이 최적화로 나타났다.2. Q10의 바인딩 버퍼 강도는 농도가 약한 10 mM에서 더많은 피크가 검출되었다.3. SELDI-TOF MS 분석에 적합한 수수 종자단백질 추출버퍼로는 2~10 kDa 범위에서는 sodium borate 버퍼와10~20 kDa 범위에서는 phenol 버퍼로 분석되었다.

Cereal seeds, sorghum, foxtail millet, hog millet, adlay, and corn are traditionally used as health assistant as well as energy supplying food in Korea. While beneficial phytochemicals to human have revealed in cereals, the information on peptides from cereals is far less accumulated than major reserve protein. Here, we analyzed peptide profiles using surface enhanced laser desorption/ionization time of flight mass spectrometry (SELDI-TOF MS) in cereal seeds for construction of peptide information and attempted to develop peptide biomarkers for cereal identification. To optimize the analysis condition of SELDI-TOF MS, the effect of dilution factor on binding affinity to protein chips was tested using CM10 and Q10 arrays. Peptide clusters were significantly different at the level of 0.01 p-value. Peak spectra were the most stable in 1:50 of dilution factor in both chip arrays. Numbers of detected peak of 5 cereal seeds were 131 in CM10 and 74 in Q10 array. Each cereal was grouped as a cluster and well discriminated into different cluster in the level of 0.01 p-value. Numbers of potentially identified peptide biomarkers are 11, 13, 9, 5 and 12 in sorghum, foxtail millet, hog millet, adlay and corn, respectively. This study demonstrates that each cereal seed have own distinguishable specific peptides although their function are not identified yet in this study. In addition, the proteomic profiling using SELDI-TOF MS techniques could be a useful and powerful tool to discover peptide biomarker for discrimination and assess crop species, especially under 20 kDa.

“Jokyoung”, a new bread making wheat cultivar, was developed from the cross between “Seri 82”, a hard white wheat from CIMMYT, Mexico and “Keumkang”, a hard white wheat with high milling rate and early maturing from Korea by National Institute of Crop Sci