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Author Topic:   Definition of Life
inkorrekt
Member (Idle past 4944 days)
Posts: 382
From: Westminster,CO, USA
Joined: 02-04-2006


Message 40 of 77 (337092)
07-31-2006 10:44 PM
Reply to: Message 39 by RAZD
07-25-2006 9:23 PM


Re: ... re membrane your cell
Perhaps a system of membranes formed of D-amino acids and that left L-amino acids in concentrated soups ... As yet we don't know

I like the last part of your post that "we do not know". The soup of D-and L-forms of amino acids will be biologically useless as the D-forms act as biological poisons.


This message is a reply to:
 Message 39 by RAZD, posted 07-25-2006 9:23 PM RAZD has responded

Replies to this message:
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inkorrekt
Member (Idle past 4944 days)
Posts: 382
From: Westminster,CO, USA
Joined: 02-04-2006


Message 42 of 77 (337324)
08-01-2006 11:23 PM
Reply to: Message 41 by Wounded King
08-01-2006 6:31 AM


Re: Optical isomer issues
Could you be more specific? How do D-forms act as biological poisons?

All biological reactions are carried out through enzymes. Enzyme must have a substrate(Substrate is a substance which is acted upon by the enzyme to give the product) L-forms are natural substrates. But, D-forms act as enzyme inhibitors.D-forms compete with the substrate for the active site on the enzyme. The primordial soup had the enzyme inhibitors so that nothing could proceed further.


This message is a reply to:
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Replies to this message:
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inkorrekt
Member (Idle past 4944 days)
Posts: 382
From: Westminster,CO, USA
Joined: 02-04-2006


Message 49 of 77 (337552)
08-02-2006 9:36 PM
Reply to: Message 43 by Wounded King
08-02-2006 3:05 AM


Re: Optical isomer issues
The substrate of an enzyme can be any one of a huge number of molecules indeed there are enzymes that convert L-amino acids into D-amino acids.

Yes, you are right on. these enzymes are known as racemase enzymes. They are not present in every cell.If they are present, then all reactions will proceed. There will not be any enzyme inhibition. But, in nature, this is not the case. Threre are specific control mechanisms modulating cellular activity. What happens if there is no control? This is when we develop some diseases known as Metabolic disorders. For example, if Phenyl alanine is not metabolized, then it accumulates. The clinical condition is known as Phenylketonuria.

Random chemical reactions cannot and should not occur. If they did, then there will be chaos and severe metabolic disorders.


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inkorrekt
Member (Idle past 4944 days)
Posts: 382
From: Westminster,CO, USA
Joined: 02-04-2006


Message 50 of 77 (337553)
08-02-2006 9:39 PM
Reply to: Message 43 by Wounded King
08-02-2006 3:05 AM


Re: Optical isomer issues
Do you have any evidence to support your contention that D-amino acids are general inhibitors of enzyme activity?

In the brain, Phenylalanine is converted into hydroxy phenylalanine by the enzyme phenyl alanine hydroxylase. L-Phenylalanine is the substrate. But, D-Phenylalanine is an inhibitor of this enzyme.


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Replies to this message:
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inkorrekt
Member (Idle past 4944 days)
Posts: 382
From: Westminster,CO, USA
Joined: 02-04-2006


Message 52 of 77 (337950)
08-04-2006 4:43 PM
Reply to: Message 51 by Wounded King
08-03-2006 2:54 AM


Re: Optical isomer issues
Which is interesting but one D-amino acid acting as an inhibitor of a specific enzyme is by no means clear evidence that D-amino acids are general inhibitors of enzyme activity
.

You are wrong. Go and check any basic text book in biochemistry.


This message is a reply to:
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Replies to this message:
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inkorrekt
Member (Idle past 4944 days)
Posts: 382
From: Westminster,CO, USA
Joined: 02-04-2006


Message 54 of 77 (339883)
08-13-2006 8:56 PM
Reply to: Message 53 by Wounded King
08-05-2006 2:46 AM


Re: Optical isomer issues
My time is valuabe. If you are so serious in learing, go to any library. I am not your teacher.

This message is a reply to:
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