Beijing Agricultural University

Separation of corn albumins and globulins by improved lactate-PAGE procedure
--T. M. Song, D. H. Zheng, Q. S. Yang and G. H. Song

An acidic lactate-PAGE procedure was developed from the basic method of wheat cultivar electrophoretic identification (Draper, 1987), but modified in extraction solution, polyacrylamide concentration, the constitution of the stock solutions and pH of buffer solution (Table 1). This procedure was proved to be suitable for separating albumin and globulin fractions of corn seed proteins and had strong resolving power, so that it could be used in corn cultivar identification, purity testing and other research purposes.

Table 1. Recipes for stock, extraction, and buffer solutions.
Gel mixed volume
Stock solutions separate concentrate
1. Acr 95g Bis 3.8g H2O 500ml 14ml
2. Sodium lactate 2.8ml+lactic acid to pH 3.2 H2O 100ml 2ml
3. Ascorbic acid 0.48g ferrous sulphate (7H2O) 8ml H2O 100ml 2ml 1ml
4. Sodium lactate 3ml+lactic acid to pH 5.6 H2O 100ml 1ml
5. Acr 26g Bis 5.2g H2O 200ml 2ml
6. Ap 11.41g H2O 100ml 80µl 80µl
each +2ml H2O
Extraction: 0.5M NaCl 100ml sucrose 15g methyl green 3mg
Buffer: Glycine 4g+lactic acid to pH 3.4 H2O 2000ml

Figures 1 and 2 show the electrophoregrams of 11 corn inbreds and 11 hybrids. It is very clear that every inbred or hybrid has its own specific band pattern distinguishable from the others. These patterns are also very stable and repeatable, so could be considered as a kind of 'fingerprint'.

Based on the mobility, the electrophoregrams were classified into four groups designated as a, b, g and wrespectively with three common bands as their boundary markers (Fig. 1). a was the fast moving, w the slow moving, and b and g the intermediate groups.  g and w were the main groups in cultivar identification.  They included 25-32 bands, most of which were very clear and distinctive.  It probably indicated the genotypic characteristics.

Figure 1. Lactate-PAGE of albumins and globulins from 11 inbred seeds. 1) Gy237, 2) 478, 3) Ye4, 4) 8112, 5) Gy798, 6) Mo17, 7) Gy246, 8) Zong31, 9) Gy220, 10) 5003, 11) 1127.

Figure 2. Lactate-PAGE of albumins and globulins from 11 hybrid seeds. 1) Gy237x478, 2) F135x1127, 3) Bs3xBs5, 4) T23xW3-9, 5) Ye4x8112, 6) Dan340x478, 7) Zong31x5003, 8) Gy220x1127, 9) Ye4xGy798, 10) Gy237x8112, 11) Zong31xGy246.

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