Some enzymatic properties of the purified glucose isomerase of Streptomyces ahygroscopicus were examined by means of different methods, such as ultraviolet spectrum (UV), infrared spectrum (IR), amino acid composition analysis and polyacrylamide gel electrophoresis (PAGE), sodium dodecyl sulfate polyacrylamide gel electrophoresis (SDS-PAGE),0.2mm thin-layer electrophoresis (TLE).The Streptomyces ahygroscopicus glucose isomerase was found to consist of one subunit by SDS-PAGE. The molecular weight of the enzyme determined by polyacrylamide gel electrophoresis in a continuous molecular sieve gradient method was 49700. The pI of the enzyme determined by 0.2mm thin-layer electrophoresis method was 5.2. Large differences were found in the amino acid composition compared with the enzymes from other sources.