If you want to purity a DNA-binding protein from a crude mixture of protains at
ID: 149843 • Letter: I
Question
If you want to purity a DNA-binding protein from a crude mixture of protains at pH 7, should you use a DEAE-cellulose or a CM-cellulose column (see the fgure below)? Explain your reasoning Weak anion exchanger (DEAE) Strong anion exchanger ("Q) Weak cation exchanger (CM Strong cation exchanger ('S") Match the items in the left column to the appropriate blanks in the sentences on the right Reset Help DEAE At pH 7a DNA-binding protein is expected to cary an excess charge that wil lead to favorable binding to the charge on the DNA molecule (e.g, histones are charged). A charged protein will bind to a column carrying an charge. Thus, at pH7 cellulose is expected to bind to a CM DNA-binding protein. Kesetj neip DEAE At pH 7a DNA-binding protein is expected to carry an excess ) charge that will lead to favorable binding to the charge on the DNA molecule (eg, histones are charged). A charged protein will bind to a column carrying an charge. Thus, at pH-7 cellulose is expected to bind to a CM DNA-binding protein. positivelyExplanation / Answer
At pH 7, DNA binding protein is expected to carry an excess + charge that will lead to favourable binding to the - charge on DNA molecule (eg. Histones are highly positively charged). A positively charge protein will bind to a column carrying excess - charge. Thus at pH 7, CM cellulose is expected to bind to DNA binding protein.