To investigate effects of the different levels of methionine and its replacement by methionylmethionine on expression of casein αs1 gene in cultured bovine mammary epithelial cells, respectively.

The combination of Na+ with alanine dipeptide (AD) in gas phase has been studied using den-sity functional theory at the level of B3LYP/6-311++G**,and six Na+-AD complexes were obtained,in-cluding two bidentate and four monodentate ones.

The coordination of dipeptide of tryptophan (Trp-Trp) with bivalent metal ion (Cu2+, Ca2+or Zn2+) was studied by ultra-violet absorption spectrometry (UV) and it was found Trp-Trp could coordinate with Cu2+, Ca2+or Zn2+.

The mode of the interaction between Tyr-Tyr and DNA has been examined by the reversion of its maximum absorption wavelength of the absorption spectra,and calculated the binding constant of Tyr-Tyr to DNA.