Date: Thu, 09 Jan 1997 15:36:55 -0700 (MST)
From: "Terry Mulcahy 272-5792; fax 272-9107" <TMULCAHY@medusa.unm.edu>
Subject: DNA Synthesis
To: abrfhyp@cco.caltech.edu
Return-path: <cairo@sc3101.med.buffalo.edu>
Received: from SC3101.MED.BUFFALO.EDU by MEDUSA.UNM.EDU (PMDF V5.0-5 #5028)
id <01IB7NMSBEQC007M7D@MEDUSA.UNM.EDU> for TMULCAHY@MEDUSA.UNM.EDU; Tue,
29 Oct 1996 10:44:31 -0700 (MST)
Received: from 128.205.166.188.med.buffalo.edu ([128.205.166.188])
by SC3101.MED.BUFFALO.EDU with SMTP; Tue, 29 Oct 1996 12:48:46 -0500 (EST)
Date: Tue, 29 Oct 1996 11:46:37 -0500
From: Alfred Cairo <cairo@sc3101.med.buffalo.edu>
Subject: Re: Trityl monitoring
X-Sender: cairo@sc3101.med.buffalo.edu
To: "Terry Mulcahy (505)277-5792; Fax: 277-5389" <TMULCAHY@MEDUSA.UNM.EDU>
Message-id: <1.5.4.32.19961029164637.006fb4c0@sc3101.med.buffalo.edu>
MIME-version: 1.0
X-Mailer: Windows Eudora Light Version 1.5.4 (32)
Content-type: text/plain; charset=us-ascii
At 10:31 AM 10/25/96 -0700, you wrote:
I still see the numbers jump
>around a lot during every sysnthsis. Any ideas? Or is the trityl monitor a
>useless appendage? Thanks for any suggestions or thoughts. TM
>
>
Hi Terry,
We've also had our 394 retrofitted, over a year ago, and experienced the
same problems. I think it is a less dependable method for chemistry
monitoring, compared with trityl absorbance monitoring, which we carried out
using a fraction collector and spectrophotometer. The major advantage of
course is time savings, but if TM is the extent of your QC, you could
easily get into trouble, especially for longer-mers : ) I believe ABI's
user bulletin talks about the limitations. We use the monitors only as
indicators of serious coupling problems. Products are QC'd by CGE.
To get our monitors to function better, we watched the monitoring cycle to
be certain that the TCA delivery is sufficient to remove all DMT prior to
the noise monitoring step. Increase delivery time if necessary (flow rates
assumed to be OK). Time required will also depend on synthesis scale.
The pulsed deliveries of TCA, as found in the standard program with no
monitoring, is probably a more efficient way of detritylation compared with
the constant flow TCA delivery necessary for trityl monitoring. For this
reason we monitor only at every 10 couplings.
Hopes this helps,
Al
````````````````````````````````````````````````````````
Alfred Cairo
Biopolymer Facility, DNA Laboratory
Roswell Park Cancer Institute
Elm & Carlton Sts.
Buffalo, NY 14263 USA
716-845-8314
fax -7621
cairo@sc3101.med.buffalo.edu