13 Kinetics of the Nonbiological Decomposition and Racemization of Amino Acids in Natural Waters
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JEFFREY L. BADA
1
Department of Geological Sciences, Hoffman Laboratory, H a r v a r d University, Cambridge, Mass. 02138
Amino
acids
variety
of nonbiological
dissolved
in natural
of most of these reactions 0°C.
The
metal
ion catalyzed
slow,
indicating
waters
fastest
would
reaction
oxidation;
that
amino
undergo
little
acids in natural racemized
dissolved
nonbiological years.
are of biological
at neutral
pH.
it is suggested
might
that the
be used to calculate
dissolved
amino
a
rates
pH
and
to be a is
in
fairly natural
decomposition Since
origin,
the
amino
they
should
acids
are
The slow racemization
of
amino acids in the sea and other natural and
The
appears
be largely of the L-configuration. However, slowly
undergo
even this reaction acids
of a thousand
waters
can
reactions.
are very slow at neutral
decomposition
even over a period
waters
decomposition
waters
racemization residence
amino is
discussed,
of amino
time or "age" of
acids the
acids.
T i T o s t o f t h e a m i n o acids w h i c h o c c u r i n t h e p r o t e i n s o f o r g a n i s m s , a n d also a f e w n o n p r o t e i n a m i n o acids, h a v e b e e n f o u n d d i s s o l v e d i n n a t u r a l w a t e r s ( J , 2, 3, 4, 5, 6, 7, 8, 9 ) . T h e c o n c e n t r a t i o n s r a n g e f r o m a b o u t 1 to 20
p e r liter. T h e s e d i s s o l v e d a m i n o acids differ f r o m t h e
a m i n o acids associated w i t h t h e p a r t i c u l a t e o r g a n i c m a t t e r i n n a t u r a l waters i n that t h e y are free a n d n o t b o u n d i n a p e p t i d e o r p o l y m e r i c l i n k a g e . T a b l e I s u m m a r i z e s some o f t h e a m i n o acids a n d concentrations w h i c h have been reported.
A m i n o acids n o t i n c l u d e d i n t h e t a b l e b u t
w h i c h m a y b e present i n l o w concentrations i n n a t u r a l waters i n c l u d e Present address: Scripps Institution of Oceanography, University of California at San Diego, La Jolla, Calif. 92037. 1
309 Hem; Nonequilibrium Systems in Natural Water Chemistry Advances in Chemistry; American Chemical Society: Washington, DC, 1971.
310
NONEQUILIBRIUM SYSTEMS IN N A T U R A L WATERS
Table I. Location
(Ref.)
Ala
Downloaded by FUDAN UNIV on January 17, 2017 | http://pubs.acs.org Publication Date: June 1, 1971 | doi: 10.1021/ba-1971-0106.ch013
Asp
a
I r i s h S e a (2) surface w a t e r 54° 0 0 ' N 3° 2 0 ' W P a c i f i c O c e a n (4) 32° 3 2 ' Ν 120° 3 0 ' W depth = 200m d e p t h = 1000m depth = 3120m York River estuary, V i r g i n i a (δ) Petroleum Brine W a t e r s (3) Uinta Basin, Utah G e o l o g i c a l age of formation, tertiary B l a c k Sea (9) surface 150 meters
A m i n o A c i d Concentrations Glu
Gly
Leu + Iso
6
6
2
4
2
3 5 6
2
