Invalid ring notation for reducing sialic acid

[ReneRanzinger]

Describe the bug
When starting the structure with a reduced Sialic acid an invalid GlycoCT is generated.

RES
1b:o-dgro-dgal-NON-2:6-0:0|1:a|2:keto|3:d|1:aldi
2s:n-acetyl
LIN
1:1d(5+1)2n

That 2:6-0:0 notation is incorrect the 2:6- should be gone.

To Reproduce
Steps to reproduce the behavior:

1. Go to 'Monosaccharide'
2. Click on 'Sialic acid'
3. Click into the canvas -> OK
4. See error in GlycoCT

Expected behavior
Valid GlycoCT

Desktop (please complete the following information):

• OS: iOS
• Browser: safari

[akulmehta]

Thanks Rene, could you tell me what is the expected GlycoCT exactly?

[ReneRanzinger]

RES
1b:o-dgro-dgal-NON-0:0|1:a|2:keto|3:d|1:aldi
2s:n-acetyl
LIN
1:1d(5+1)2n

Just remove the "2:6-".

[ReneRanzinger]

Actually, the aldi can not be on 1 due to the acid. 2:aldi. But that would be a good question what sequence reader will do with it. I am not sure we ever had the case of a Sialic acid alditol.

[akulmehta]

@ReneRanzinger I confirmed with some chemists and it is possible to have sialic acid linked to a linker and have alditol present. So we will need to cover this case.

Is there an issue if represented as follows?

RES
1b:o-dgro-dgal-NON-0:0|1:a|2:keto|3:d|2:aldi
2s:n-acetyl
LIN
1:1d(5+1)2n

note the 2:aldi above

[ReneRanzinger]

@akulmehta That should be OK.