Date: Wed, 4 Mar 2026 02:49:48 +0000
Dear Clemens and Ivan,
Thank you for your explanation regarding the extra peaks and the glucose spectra.
In TopSpin, I used SR = 0 to set the chemical shift in my spectrum, which
is not referenced to TSP or DSS.
The alpha C6 also shows an additional peak, which I believe is similarly related
to the alpha C5 proton, but this extra peak is absent in C6-deuterated glucose.
Best regards,
Weixing
> From: main_at_ammrl.groups.io On Behalf Of Vuckovic, Ivan, Ph.D. via groups.io
> Sent: Tuesday, March 3, 2026 6:59 PM
> To: main_at_ammrl.groups.io
> Subject: Re: [AMMRL] : Puzzle of glucose HSQC
Hi Weixing,
I agree with Clemens — those are indeed HSQC-COSY artifacts, and the
additional peaks correspond to correlations of C-3 and C-5 with proton H-4.
However, the chemical shifts of H-3 and H-5 in your spectrum differ noticeably
from the literature values (HMDB and BMRB). What are your experimental conditions
(solvent, pH, temperature), and what reference you used for chemi cal shift calibration?
Your resolution in the F1 dimension is remarkable — the HSQC correlation
peaks of C-3 and C-5 are clearly resolved, which is not the case in database spectra.
For reference, I am attaching a full assignment of glucose HSQC spectra, along
with additional examples of HSQC-COSY artifacts.
Best regards,
iv
________________________________
> From: main_at_ammrl.groups.io on behalf of Anklin, Clemens via groups.io
> Sent: Tuesday, March 3, 2026 3:37 PM
> To: main_at_ammrl.groups.io
> Subject: [EXTERNAL] Re: [AMMRL] : Puzzle of glucose HSQC
Hi Weixing
HSQC's can show COSY type peaks when the acquisition time in the indirect
dimension gets long. Would these peaks by any chance align with the C4
protons? The sequence hsqcedetgpsisp2.4 suppresses these COSY type artefacts.
Clemens
On 3/3/2026 2:38 PM, Zhang, Weixing via groups.io wrote:
Dear Colleagues,
The attached picture shows the HSQC cross-peak of C3 and C5 in natural
abundance β-glucose.
Coupling to the C2 and C4 protons makes C3 appear as a triplet, but I am
unsure what the small peak located ~32 Hz to the right of the main signal
represents.
Similarly, for C5 there is also a small peak on the right side, approximately
20 Hz away from the main peak.
I would appreciate any insight into the origin of these additional peaks.
Thank you in advance.
Best regards,
Weixing
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