It is best to have a pure sample, if possible. Purity should be determined by SDS-PAGE, or an equivalent method. However, if the molar amount of the desired sample substantially exceeds that of an impurity
(e.g., by a factor or 100), then an impure sample can be sequenced.
blotting onto a PVDF membrane of an impure sample fractionated by
SDS-PAGE is a reliable method for obtaining pure material.
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Samples should be provided in as small a piece of PVDF as possible. if one is to err, they should err on the side of making the piece smaller
than larger.
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There is none, per se. a rough rule of thumb is that the higher
the molecular weight, the more material is needed and the fewer the number
of cycles that can be interpreted. Ideally, 100-1000 picomoles would be
backod. However, depending on chemical and primary structure factors,
small peptides could yield excellent sequence with substantially less
than 100 picomoles.
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Provision of samples can be "by hand," by mail,
or by courier. if samples are not dry, then they should be sent by overnight courier to
the laboratory, preferably frozen on dry ice.
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We charge $250 to set the machine up and to provide up to 5 cycles
of information. Each subsequent cycle costs $25. A 25% surcharge is
made for non-academic samples.
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The answer is a function of the amount of sample (direct proportionality), its molecular weight (inverse proportionality), and
its sequence. Given that answers to these questions are favorable,
sequences of 50 cycles of more are possible. However, one should expect
substantially fewer, on average.
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