Cell Surface Engineering by a Modified Staudinger Reaction
Science, 2000 · paper · Chemistry
Presents a modified Staudinger reaction that couples an azide with an engineered triarylphosphine to form a stable amide bond. Azides introduced into cell-surface sugars were labeled with a biotinylated phosphine, and the authors suggest it could work inside cells.
Checked: PDF from people.bu.edu, fetched 4 Oct 2026. Page numbers are those of that PDF.
2 findings
Substance Text: "reaction at pH 6.5 produced 75% of the fluorescence signal observed at pH 7.4 (Fig. 4C)", but in Fig. 4C (PDF page 3) the pH 6.5 histogram peaks at about 10-13 units and the pH 7.4 histogram at about 40 units on the logarithmic axis, roughly half a decade apart (about 30%, not 75%).
- p. 2 Results text, right column, pH dependence sentence
75% of the fluorescence signal observed
- p. 2 Fig. 4C, histograms labelled pH 6.5 and pH 7.4 on logarithmic fluorescence axis (0.1 to 1000)
pH 6.5
- p. 2 column 3, text on pH dependence
reaction at pH 6.5 pro-
Only the authors can say what is right here.
Judge's note: Rendered Fig. 4 from the PDF at 5x. Fig. 4C is on PDF page 3 (the sentence is on page 2). The x axis is logarithmic, 0.1 to 1000, about 113 px per decade in my render. The pH 6.5 (dotted) peak sits just right of the 10 tick and the pH 7.4 (open) peak about 57 px further right, near 40; the two distributions overlap only in their tails. A 75% signal would shift the peak by only about 0.12 decade (about 14 px), so the histograms would largely coincide. Both histograms have similar width on the log axis, so mean versus mode does not account for the difference. The figure legend and text give no other definition of the 75% (for example a different replicate or background subtraction). Read from a printed histogram, so the exact ratio is approximate, but the gap between 0.5 and 0.12 decade is well beyond reading error. Only the authors can say whether the text or the plotted panel is right.
Second check: another model agreed
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Substance Note 9: "NaN3 (78 mg, 1.39 mmol)"; 78 mg of sodium azide is 1.20 mmol, and 1.39 mmol would be about 90 mg.
- p. 4 References and Notes, note 9 (synthesis of compound 3)
NaN3 (78 mg, 1.39 mmol)
- p. 4 References and Notes, note 9
NaN3 (78 mg, 1.39
Only the authors can say what is right here.
Judge's note: Rests on outside knowledge: the molar mass of NaN3 is 65.01 g/mol. The crop of note 9 on page 4 shows "NaN3 (78 mg, 1.39 mmol)" as quoted. 78/65.01 = 1.20 mmol; 1.39 x 65.01 = 90.4 mg; a 16% gap, beyond rounding. 1.39 is 1.2 x 1.16 mmol (1.2 equivalents of the mannosamine), so one of the two numbers was probably miscalculated, but only the authors can say which. The other mass and mmol pairs in the note agree with each other on the same basis (250 mg and 1.16 mmol; 991 mg and 5.80 mmol; 25 mg and 0.095 mmol), and nothing in the note mentions a purity correction or a different salt.
Second check: another model agreed
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6 minor (typos and the like; most checked by the judge only)
Wording Note 10: "KI (4.30 g, 25.0 mmol)"; 4.30 g of potassium iodide is 25.9 mmol, and 25.0 mmol would be 4.15 g.
- p. 4 References and Notes, note 10 (synthesis of phosphine 4)
KI (4.30 g, 25.0 mmol)
Only the authors can say what is right here.
Judge's note: Rests on outside knowledge: the molar mass of KI is 166.00 g/mol. The crop of note 10 on page 4 shows "KI (4.30 g, 25.0 mmol)" as quoted. 4.30/166.00 = 25.9 mmol; both figures are given to three significant figures and differ by 3.6%, more than rounding allows (4.295-4.305 g gives 25.87-25.93 mmol). KI is in roughly tenfold excess, so the slip has no practical consequence; rated minor. Either number could be the misprint.
Second check: another model agreed
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Typo Misspelling: "The phospine and the azide react" should read "phosphine".
- p. 1 Body text, middle column, paragraph beginning "The Staudinger reaction occurs"
The phospine and the azide react
Judge's note: Crop of page 1, middle column, shows "phosphine oxide. The phospine and the azide react" as printed; the word is spelled "phosphine" elsewhere in the same paragraph.
Second check: none (judge only)
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Typo Unmatched closing parenthesis: "[1 mM in phosphate-buffered saline (PBS), pH 7.4)]"; the ")" after 7.4 has no opening partner.
- p. 1 Body text, right column, paragraph beginning "Jurkat cells were incubated"
[1 mM in phosphate-buffered saline (PBS), pH 7.4)]
Judge's note: Crop of page 1, right column, shows "compound 5 [1 mM in phosphate-buffered saline (PBS), pH 7.4)] for 1 hour". One opening and two closing parentheses inside the square brackets.
Second check: none (judge only)
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Typo Misspelling in the Fig. 3 legend: "a water-soluble biotinlyated phosphine" should read "biotinylated".
- p. 2 Fig. 3 legend, part (A)
a water-soluble biotinlyated phosphine
- p. 2 Fig. 3 legend, panel A
water-soluble biotinlyated phosphine
- p. 2 Fig. 3 caption
biotinlyated
- p. 2
a water-soluble biotinlyated phosphine for quantifying
Judge's note: Crop of the Fig. 3 legend on page 2 shows "biotinlyated" in part (A) and the correct "biotinylated phosphine 5" in part (B) two lines below.
Second check: none (judge only)
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Typo Duplicated word: "which raises the the possibility of disulfide bond reduction".
- p. 3 Body text, left column, paragraph beginning "To satisfy the requirement of chemical orthogonality"
which raises the the possibility of disul-
- p. 3 Left column, paragraph on chemical orthogonality
which raises the the possibility
- p. 3 left column, first full paragraph
raises the the possibility of disul-
- p. 3 column 1, paragraph 2
raises the the possibility
Judge's note: Crop of page 3, left column, shows "agents, which raises the the possibility of disul-" on a single line, so it is not a line-break or extraction duplication.
Second check: code check
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Typo Reference 15: "J. C. M vanHest and D. A. Tirrell"; the period after the initial M is missing and the surname is run together ("vanHest").
- p. 4 References and Notes, ref. 15
J. C. M vanHest and D. A. Tirrell
Judge's note: Crop of the reference list on page 4 shows "15. J. C. M vanHest and D. A. Tirrell, FEBS Lett. 428, 68 (1998)." Every other entry in the list puts a period after each initial (for example "K. J. Yarema", "V. W. Armstrong"), so the missing period is a defect on the page itself. That the surname is properly written "van Hest" is the usual Dutch form and is not verifiable from the files.
Second check: none (judge only)