C&EN Classifieds
Home | This Week's Contents  |  C&EN ClassifiedsSearch C&EN Online

 
Millennium Special Report
C&EN 75th Anniversary Issue
 
Related Stories

SINGLE-HANDED REPLICATION
[C&EN, Feb. 19, 2001]

Magnetic Fields And Unpolarized Light Have Hand In Chirality
[C&EN, June 26, 2000]

Molecular Architectures
[C&EN, Apr. 19, 1999]

Related Sites
E-mail this article to a friend
Print this article
E-mail the editor
 
 
 Table of Contents
 C&EN Classifieds
 News of the Week
 Cover Story
 Editor's Page
 Business
 Government & Policy
 Science/Technology
 Concentrates
  Business
  Government & Policy
  Science/Technology
 Education
 ACS News
 Calendars
 Books
 Digital Briefs
 ACS Comments
 Career & Employment
 Special Reports
 Letters
 Awards
 People
 Newscripts
 Nanotechnology
 What's That Stuff?
 Pharmaceutical Century

 Hot Articles
 Safety  Letters
 Chemcyclopedia

 Back Issues

 How to Subscribe
 Subscription Changes
 About C&EN
 Copyright Permission
 E-mail webmaster
NEWS OF THE WEEK
SCIENCE
May 7, 2001
Volume 79, Number 19
CENEAR 79 19 pp. 12
ISSN 0009-2347
[Previous Story] [Next Story]

A PREFERENCE FOR LEFT-HANDEDNESS
Certain faces of calcite crystals selectively adsorb l-amino acids

REBECCA RAWLS

Left-handed amino acids are a hallmark of life. Recent geochemistry experiments hint at one way this chiral selectivity may have originated.

MULTIFACETED Hazen displays calcite crystal with mirror-image faces.
The common mineral calcite has crystal surfaces that are mirror images of one another. Robert M. Hazen, staff scientist at Carnegie Institution of Washington's geophysical laboratory; Timothy R. Filley, assistant professor of environmental chemistry at Purdue University; and Glenn A. Goodfriend, research associate professor of geology at George Washington University, find that the l form of certain amino acids adheres selectively to one of calcite's crystal faces and the d form, to the other [Proc. Natl. Acad. Sci. USA,
98, 5487 (2001)].

Although this preference does not appear to hold for every amino acid the researchers have tested, it's true for several, including aspartic acid, glutamic acid, and alanine. These three, along with nonchiral glycine, are the amino acids thought to have been most abundant in a prebiotic world.

"Chiral selection requires three distinct points where you have some sort of bonding between the molecule and the surface," Hazen explains. "I think of it as the 'bowling ball problem.' If you are a left-handed person, you can't use a right-handed bowling ball because the three holes are arranged with the wrong topology."

Earlier studies have considered selective adsorption of d- or l-amino acids onto minerals like quartz, which themselves exist in d and l forms. But calcite, which is not chiral but forms mirror-image crystal surfaces, was also worth examining, the researchers thought. "Calcite crystal surfaces are, and always have been, abundant on Earth," Hazen notes. "We also know that biological systems today take advantage of the strong adsorption between amino acids and calcite."

[Previous Story] [Next Story]



Top


Chemical & Engineering News
Copyright © 2001 American Chemical Society


C&EN Classifieds
Home | Table of Contents | News of the Week | Cover Story
Business | Government & Policy | Science/Technology
Chemical & Engineering News
Copyright © 2001 American Chemical Society - All Right Reserved
1155 16th Street NW • Washington DC 20036 • (202) 872-4600 • (800) 227-5558


CASChemPortChemCenterPubs Page