left handed...right handed...

[victor]

Hi, it's me again, Victor..I wanna ask a bit about protein..
Actually, I wonder that is protein chiral or not?? some books said that protein is racemic but what I think that inside human body, protein is made from S-amino acid......
so, if those S-amino acid stuck together to form, let's say secondary structure of protein, would the protein will be S configurated also???

racemic = mix of R and S. So, they eliminate each other's rotation.
R = rectus, right rotation
S = sinistral, left rotation

[victor]

Briefly, are proteins inside our body levorotatory??? or neutral??

[Nite]

yes u are right.. The amino acids that are synthesis naturally (biologically) consist of a majority of L-aa and little D-aa. While those synthesis in the lab is always racemic (i.e. amount of D : L = ~1)..

Most of the amino acids in our body are L-amino acids.. consequently the secondary structure of the proteins shud be made up of L-aa as well..

i remember dat i read somewhere b4 that D-aa are found in minute amount in some part of human brain. The drop in the level of D-aa in that part is shown to be correlated with diseases like Alzheimer's and Parkinsons..

I can't find the link now....

There are some topics in this forum that talk about L and D-aa:

about4027.html

about2110.html&highlight=damino+acids