By means of intrinsic fluorescence measurements,total free sulfhydryl (SH) quantitation,non-reducing and reducing SDS-PAGE analysis and AFM,the effect of pH on the forming of the N-terminal domain aggregation of high molecular weight glutenin subunits (HMW-GS) 1Dx5 (1Dx5-N) was investigated.The results show that (1) in comparison with the acidic and alkaline conditions,the maximum emission wavelength of 1Dx5-N displays a blue shift under the neutral pH condition (pH 7. 0),indicating that 1Dx5-N under the neutral pH condition has a higher degree of aggregation; (2) in comparison with the acidic and alkaline conditions,the 1Dx5-N under the neutral condition is of a lower total free sulfhydryl (SH) content with more dimers and polymers,indicating that,in the ag- gregation of 1Dx5-N,the neutral condition is more helpful and the disulfide bonds play an important role; and (3) under the neutral pH condition,the aggregation of greater particle size forms,which further proves that the neutral pH condition is superior to the acidic and alkaline conditions in terms of the aggregation of 1Dx5-N.Thus,the rationality of the flour product processing under the neutral condition is demonstrated at the molecular level.