Snape -- blood debt to James?

[sym_2_one]

No: HPFGUIDX 100130

I haven't posted in a really long time, but I've read the Snape/Harry 
mutual hate theories, and I have one of my own spawned from a post I 
read last week:

Would it be possible that the reason why Snape keeps trying to help 
Harry is because his blood debt to James was compromised by the 
Potters' death?  Is it possible that Snape feels somewhat guilty about 
 their deaths, and has moved on to Harry because of that?  I realize 
that I'm making a huge assumption here, but, if Snape was a D.E. and 
he alerted Dumbledore that Voldemort was after the Potters, could it 
be possible that Snape knew that at least one of the Potters' friends 
had turned traitor? Why else would Dumbledore believe Sirius' story so 
completely in POA without any evidence to support it besides the words 
of two thirteen year old wizards?  And even if Snape did not know, I 
believe that in GOF Dumbledore says that Snape turned to the good side 
just before Voldemort's downfall.  Is it possible that he did this in 
response to his blood debt to James?  Found out what Voldemort was 
up to and tried to stop it?  And in his failure to save James' life 
(i.e. repay the debt), had to turn to Harry instead?  JKR says that 
this type of connection between wizards is extremely powerful.  I just 
want to know others opinion on the matter. 

"sym_2_one"