For longer versions of these and other
Molecules stories, visit www.sciencenews.org
Test ranks best
molecules for job
By Rachel Ehrenberg
A new method that ranks compounds’
chemical attractiveness could help
chemists discern promising drug candi-
dates from duds. Researchers have come
up with a way to quantify a compound’s
drug potential that moves beyond
simply “hot or not.”
The approach “takes things a step fur-
ther, looking at multiple factors instead
of yes-no,” says chemical informati-
cist David Wild of Indiana University
Bloomington, who was not involved with
the research.
The new technique uses eight molecu-
lar properties — such as the number of
rotatable bonds a molecule has — that
influence things like a compound’s toxic
effects or its likelihood of being absorbed
in the body. With some clever math, those
properties are turned into a number
between zero and one.
Network diagrams characterize drug
candidates (dots) for a target called
matriptase. Similar candidates are clustered together; red indicates the most
promising compounds, blue the least.
development, says study leader Andrew
Hopkins, an expert in drug discovery
and molecular design at the University
of Dundee in Scotland.
Existing screening
techniques tend to make
pass/fail judgments. The
famous Lipinski’s Rule
of Five, for example,
“Our metric suggests that you can
break some rules,” says Hopkins. “As
with people, you can tolerate some bad
behavior in someone’s personality if they
are very good in their other qualities.”
Seaweed fuels bioenergy optimism
Engineered E. coli convert cell wall component into ethanol
By Rachel Ehrenberg
An engineered bacterium that breaks
down and digests seaweed’s gummy cell
walls to yield ethanol may soon make
marine algae a serious contender as a
source of renewable fuel.
The development “makes a pretty large
leap forward,” says metabolic engineer
Hal Alper of the University of Texas at
Austin. Unlike corn and many other biofuel sources, seaweed doesn’t need arable
land, fertilizer or freshwater. If seaweed
can be efficiently munched into ethanol, it broadens the biofuel horizon, says
Alper, who was not involved in the work.
Scientists from Bio Architecture Lab,
a biofuel and renewable chemicals com-
pany headquartered in Berkeley, Calif.,
were interested in creating a biofuel
bacterium that could efficiently break
down and digest the cellular building
block of seaweed called alginate without
pretreatment with chemicals or heat.
upon the marine bacterium Vibrio splen-didus, and took a hefty chunk of Vibrio
DNA. When the team fed alginate to the
engineered E. coli, the microbes pumped
out ethanol at 80 percent of theoretical
maximum efficiency, the researchers
report in the Jan. 20 Science.
A cell wall component in this
Macro-cystis seaweed can be fed to an engineered form of E. coli to make ethanol.
