From: LARRY KLAES (ljk4@msn.com)
Date: Sat Nov 09 2002 - 05:55:05 PST
----- Original Message -----
From: Gary McMurtry
Sent: Friday, November 08, 2002 12:03 AM
To: europa@klx.com
Cc: Frank D. Carsey; F. Scott Anderson; Lloyd.C.French@jpl.nasa.gov; Arthur Lane; steven smith; cmoyer@hydro.biol.wwu.edu; David Emerson; Pamela Conrad; Nathaniel E. Ostrom
Subject: Protein Stability & Life at the Extreme
Per a UH seminar today by Harold Helgeson of UC Berkeley, proteins
have folding stability (they work best when folded into "balls") at
very low pH, like -2, and at these pH values, temperature extremes of
200+ degrees C and (important for those ice microbes on Europa &
Mars) very low temperatures also. Even at moderate pH of 6-8, many
common proteins are stable to 80-90 degrees C (Why so high? We
succumb at 40+ C), which suggests that we all have a common,
thermobarophilic ancestor. Prof. Helgeson has the thermodynamic data
to support these conclusions (he's an expert), and he suggests that
John Baross and Jody Deming's earlier data on short doubling times at
250+ degrees C from "black smoker" hydrothermal vent cultures may be
correct, i.e., these organisms are productive and actually don't care
if the compounds break down over longer exposure periods at high (or
low) temperature and pH because they are rapidly finished with them!
As someone who has directly observed apparent colonies of microbes,
probably Archaea, living in 140-200 degree C vent waters on Loihi
Seamount off Hawaii in 1996-98, this was an exciting and encouraging
seminar. The mats were white to clear, attached to sulfide-encrusted
rock and billowing in the vent waters. I've seen a lot of inorganic
hydrothermal deposits and none ever flexed or wiggled like that. Oh,
and we have video.
His research team is also working on amino acids, RNA and DNA
stability. I'll see if Prof. Helgeson has publications on the topic
and will post.
Gary
PS. Helgeson suggests that through evolution WE are the ones living
in the extreme environment, from a thermobarophilic organism's
(grandma's) point of view!
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