Proteins 



37 



CH OH 



OH 



Much of the nucleic acid obtained from nuclei belongs to this type 

 with physico-chemical properties that suggest that it is enclosed 

 within a core of proteins of the histone or protamine variety. 



Four deoxynucleotides are commonly found in samples of DN A 

 obtained from all sorts of cells. 



i. Deoxyadenylate (deoxyadenosine 5'phosphate) which is a 



purine base linked by a glycoside bond to 2-deoxyribose. It 



occurs in the form of a furanose ring and lacks an oxygen 



at the 2-carbon position. Esterified at carbon 5 is a phosphate 



residue. 



H H 



\ / 



ii. Thymidine 5 '-phosphate (thymidylate) which is composed 

 of a pyrimidine-thymine linked as in the case of adenine to 

 a 3 deoxyribose 5'-phosphate. The methyl group on the 5 

 carbon distinguishes thymine from uracil which is also a 

 pyrimidine. Uracil is a component of RNA and of 

 coenzymes prominent in carbohydrate metabolism. 



iii. Deoxyguanylate , a purine compound. 



iv. Deoxycytidinate , a pyrimidine compound. 



