and it's name should be D-Glucuronate 2-sulfate, N-sulfoglucosamine 6-sulfate. I searched on internet but could not find this kind of heparin. So could anyone give credibility that this structural compound is heparin? Atlast what is the criteria that determines whether the compound is a heparin?
This structure is exactly the same structure as found on wikipedia at the very top the page. Other variations are also shown elsewhere on that page.
Perhaps you are being misled by the presence/absence of hydrogens on the sulfate groups? The way your textbook shows it is a more physiologically relevant way as those groups would be deprotonated in normal biological conditions, but this doesn't really change the chemical structure. Heparin is normally administered as a salt.
Further, heparin is a polysaccharide chain of varying lengths (more information on that same wikipedia page) - it doesn't really make sense to say that heparin's chemical name should be "D-Glucuronate 2-sulfate, N-sulfoglucosamine 6-sulfate" - this is the name of only one disaccharide in a long, long chain. Your textbook doesn't say that either, the little "n" in the lower right corner is very important and indicates a chain of unspecified length.