how precipitation of protein by metal ions work??

Question

The material used are 5g/L albumin, casein, gelatine, and peptone..Three metals were used that are CuSO4, lead acetate, and mercury nitrate..i need to do the lab report..especially for introduction snd discussion.please...

Answer 1

Heavy metal salts, such as CuSO4 act to denature proteins in much the same manner as acids and bases. Heavy metal salts usually contain metals with high atomic weights. Since salts are ionic they disrupt salt bridges in proteins. The reaction of a heavy metal salt with a protein usually leads to an insoluble metal protein salt. Heavy metals may also disrupt disulfide bonds because of theirnhigh affinity and attraction for sulfur and will also lead to the denaturation of proteins.

The metal ion will dissociate and bind to a part of the protein. An advantage of this type of precipitation is that they have great precipitating power in a dilute solution. These ions can be classified into three groups. Ions such as Mn2+, Fe2+, Co2+, Ni2+, Zn2+, and Cd2+ will bind strongly to carboxylic acids and to nitrogenous compounds. Ca2+, Ba+2, Mg+2, and Pb+2 will mainly bind to carboxylic acids. Finally, Ag+, Hg2+, and Pb2+ will bind strongly to sulphydryl groups.