Talk:Alexa Fluor

message: The molecular mass (MM) of AlexaFlour 647 is listed in the table as 1155.06 g/mol, with a reference to Supporting Information; Esteban, Fink, et al. Fungal recognition is mediated by the association of dectin-1 and galectin-3 in macrophages. Proceedings of the National Academy of Sciences of the United States of America. 2011. Vol 108, no 34, pg 14270-14275. 10.1073/pnas.1111415108. However, this article says "The predicted molecular weight for the Alexa647 peptide is 1155.06, obs = 1155.0". Here, "Alexa647 peptide" is referencing a GGGK peptide conjugate of Alexa647. Subtracting the mass of GGGK, the Alexa647 moiety is only 784 g/mol. Looking at the chemical structure for Alexa647 given in a paper by Huber et al.Scheme 15.3; He Tian, Thomas P. Sakmar, Thomas Huber; Chapter 15 - Site-Specific Labeling of Genetically Encoded Azido Groups for Multicolor, Single-Molecule Fluorescence Imaging of GPCRs. Methods in Cell Biology, Volume 117, 2013, Pages 267-303. doi: 10.1016/B978-0-12-408143-7.00015-3. link the molecular mass of Alexa647 shouldn't be more than 844 g/mol, including a C3-amide linker. (The Alexa 647 chemical structure contains 4 SO3 = 4 × 80 = 320, 3 N = 3 × 15 = 60, 1 O = 16, 35 C = 420 , 43 H = 43; 320 + 60 + 16 + 420 + 43 = 844 g/mol). Without linker, the molecular mass of the free Alexa 647 fluorophore is probably closer to 800 g/mol. Note that the molecular mass listed on many vendor sites (1200 g/mol, for example) includes the mass of counter ions, not just the Alexa647 molecule. (They do this so when their customers dissolve a certain mass amount, they get the correct concentration of Alexa 647 when using the given "molecular weight" to convert mass to molar amount.)
Additionally, in the table of properties there is hardly any references at all for the molecular mass of most of the other Alexa Flours, and the reference for Alexa633 cites a vendor product page, where the molecular mass includes counter ions required to stabilize the product. Since the counter ions may vary from vendor to vendor, it makes the most sense to list "molecular mass" as that of the Alexa Fluor molecule itself, without counter ions. Obtaining the correct molecular masses can be done using the chemical structure formulas, which is generally known and published (e.g. the reference above). If someone bothered to do it, he/she could go over all published Alexa Flour structures and calculate proper molecular masses, citing the proper references.
Rasmusscholer (talk) 11:19, 26 October 2018 (UTC)
thread_title: Molecular Masses

message: Some quantum yields are available.
See
http://probes.invitrogen.com/handbook/tables/2068.html
This would seem to contradict some of the "comparison with other dyes" section.  —Preceding unsigned comment added by 163.1.240.129 (talk) 12:22, 10 October 2007 (UTC)
thread_title: Quantum Yields

message: Isn't rhodamine also a xanthene derivative? --Kupirijo 07:04, 1 December 2006 (UTC)
thread_title: Rhodamine

message: Rather than copying and pasting, the page should have been moved to preserve the edit history. See WP:RM. -- Beardo 15:40, 10 August 2007 (UTC)
replies: text: Done and done. -- MarcoTolo 20:05, 13 August 2007 (UTC)
thread_title:  Name change 

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thread_title:  External links modified