Mass spectrometry of a purified protein shows three mass peaks, SDS-PAGE shows t
ID: 901821 • Letter: M
Question
Mass spectrometry of a purified protein shows three mass peaks, SDS-PAGE shows three bands, while gel-filtration shows a single molecular weight and only a single amino terminal sequence is obtained. What is the best description of this sample? the sample is not pure, it contains multiple polypeptide chains. the sample is a single polypeptide, but it is modified by the addition of glucose residues, making it a glycoprotein. the sample is a single polypeptide, but it is phosphoiylated at serine and threonine residues. there is insufficient evidence to answer this question. It is possible to determine protein structures with X-ray diffraction because: The diffracted X-rays can be refocused to give an image of the object, just like a microscope. The diffracted X-rays can be used to directly obtain an image of the molecule on film. Interference between the diffracted X-rays depends on the relative position of the atoms. The X-rays are absorbed by atoms, giving a shadow where the atom was. X-rays cannot be used to determine structures.Explanation / Answer
Mass spectrometry of a purified protein shows three mass peaks, SDS-PAGE shows t