Instruct: Identify the main and secondary category of Arxiv papers based on the titles and abstracts
Query: Why high-error-rate random mutagenesis libraries are enriched in
  functional and improved proteins   Recently, several groups have used error-prone polymerase chain reactions to
construct mutant libraries containing up to 27 nucleotide mutations per gene on
average, and reported a striking observation: although retention of protein
function initially declines exponentially with mutations as has previously been
observed, orders of magnitude more proteins remain viable at the highest
mutation rates than this trend would predict. Mutant proteins having improved
or novel activity were isolated disproportionately from these heavily mutated
libraries, leading to the suggestion that distant regions of sequence space are
enriched in useful cooperative mutations and that optimal mutagenesis should
target these regions. If true, these claims have profound implications for
laboratory evolution and for evolutionary theory. Here, we demonstrate that
properties of the polymerase chain reaction can explain these results and,
consequently, that average protein viability indeed decreases exponentially
with mutational distance at all error rates. We show that high-error-rate
mutagenesis may be useful in certain cases, though for very different reasons
than originally proposed, and that optimal mutation rates are inherently
protocol-dependent. Our results allow optimal mutation rates to be found given
mutagenesis conditions and a protein of known mutational robustness.

6
The categories of this paper are: astro-ph
0
The categories of this paper are: hep-ph
4
The categories of this paper are: cond-mat
24
The categories of this paper are: dg-ga
8
The categories of this paper are: hep-ex
20
The categories of this paper are: acc-phys
1
The categories of this paper are: cs
32
The categories of this paper are: atom-ph
25
The categories of this paper are: patt-sol
27
The categories of this paper are: comp-gas
7
The categories of this paper are: hep-th
33
The categories of this paper are: plasm-ph
29
The categories of this paper are: funct-an
26
The categories of this paper are: bayes-an
11
The categories of this paper are: hep-lat
28
The categories of this paper are: alg-geom