Start2Fold

The database of hydrogen/deuterium exchange data on protein folding and stability

Entry STF0022

Alpha-subunit of tryptophan synthase (aTS)

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Protein information

Name of the protein: Tryptophan synthase alpha chain
Organism: Salmonella typhimurium (strain LT2 / SGSC1412 / ATCC 700720)
Number of residues: 268
Related UniProt entry:   P00929 (Fragment: 1 - 268)
Related PDB entry:   1BKS

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Experiment sets

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EARLY

Method: Pulse labeling HDX MS

Conditions: pH 7.8; 25.0 Celsius; Probes: monitors every possibly protected amide site

Related publication:
 PMID 15784252

Experiment details: "The refolding kinetics of aTS upon dilution from 8 M urea to 0.4 M urea was studied by analyzing the data taken over the first 100 seconds of the reaction."

Protection threshold: high protection (>30%)

Sequence: MERYENLFAQLNDRREGAFVPFVTLGDPGIEQSLKIIDTLIDAGADALELGVPFSDPLADGPTIQNANLRAFAAGVTPAQCFEMLALIREKHPTIPIGLLMYANLVFNNGIDAFYARCEQVGVDSVLVADVPVEESAPFRQAALRHNIAPIFICPPNADDDLLRQVASYGRGYTYLLSRSGVTGAENRGALPLHHLIEKLKEYHAAPALQGFGISSPEQVSAAVRAGAAGAISGSAIVKIIEKNLASPKQMLAELRSFVSAMKAASRA
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EARLY residues

20: V; 21: P; 22: F; 23: V; 24: T; 25: L; 26: G; 27: D; 28: P; 29: G; 30: I; 31: E; 32: Q; 33: S; 34: L; 35: K; 36: I; 37: I; 38: D; 39: T; 40: L; 41: I; 42: D; 43: A; 44: G; 45: A; 46: D; 47: A; 48: L; 49: E; 82: F; 83: E; 84: M; 85: L; 86: A; 87: L; 88: I; 89: R; 90: E; 91: K; 92: H; 93: P; 94: T; 95: I; 96: P; 97: I; 98: G; 99: L; 100: L; 101: M;
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INTERMEDIATE

Method: Pulse labeling HDX MS

Conditions: pH 7.8; 25.0 Celsius; Probes: monitors every possibly protected amide site

Related publication:
 PMID 15784252

Experiment details: "The refolding kinetics of aTS upon dilution from 8 M urea to 0.4 M urea was studied by analyzing the data taken over the first 100 seconds of the reaction."

Protection threshold: moderate protection (10-30%)

Sequence: MERYENLFAQLNDRREGAFVPFVTLGDPGIEQSLKIIDTLIDAGADALELGVPFSDPLADGPTIQNANLRAFAAGVTPAQCFEMLALIREKHPTIPIGLLMYANLVFNNGIDAFYARCEQVGVDSVLVADVPVEESAPFRQAALRHNIAPIFICPPNADDDLLRQVASYGRGYTYLLSRSGVTGAENRGALPLHHLIEKLKEYHAAPALQGFGISSPEQVSAAVRAGAAGAISGSAIVKIIEKNLASPKQMLAELRSFVSAMKAASRA
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INTERMEDIATE residues

12: N; 13: D; 14: R; 15: R; 16: E; 17: G; 18: A; 19: F; 70: R; 71: A; 72: F; 73: A; 74: A; 75: G; 76: V; 77: T; 78: P; 79: A; 80: Q; 81: C; 114: F; 115: Y; 116: A; 117: R; 118: C; 119: E; 120: Q; 121: V; 122: G; 123: V; 124: D;
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STRONG

Method: Native exchange in partially folded state by MS

Conditions: pH 7.8; 22.0 Celsius; Probes: monitors segments covering nearly the whole protein (~240 amids)

Related publication:
 PMID 15312776

Experiment details: "HDX of the intermediate state in 3 M urea. Unfolding studies were initiated by combining 10 μl of αTS (~340 pmol, in 10 mM phosphate (pH 7.8), 0.2 mM K2EDTA, 1 mM DTT) and 90 μl of urea solution (0–8 M urea, 10 mM phosphate (pH 7.8)) in a 1.5 ml tube. Following incubation at 22 °C for various times, 900 μl of D2O (same concentration of urea, 10 mM phosphate (pH 7.8)) were added to initiate isotope labeling. Samples used for the equilibrium studies were incubated in urea for three hours. After labeling for five seconds, hydrogen exchange was quenched by decreasing the pH and temperature to 2.5 and 0 °C, respectively. The pH was reduced with 0.5 M HCl. Mass spectra of 21 peptic fragments spanning nearly the entire sequence of aTS were used to determine the deuterium levels. The folding status of segments represented by peptic fragments from aTS incubated in 2 M or 3 M urea was determined by comparing the molecular masses of these fragments (or masses of multiple envelopes of isotope peaks) to the masses of the same peptic fragments derived from the native or unfolded references."

Protection threshold: protected in more than 50% of the molecules in 3 M urea

Sequence: MERYENLFAQLNDRREGAFVPFVTLGDPGIEQSLKIIDTLIDAGADALELGVPFSDPLADGPTIQNANLRAFAAGVTPAQCFEMLALIREKHPTIPIGLLMYANLVFNNGIDAFYARCEQVGVDSVLVADVPVEESAPFRQAALRHNIAPIFICPPNADDDLLRQVASYGRGYTYLLSRSGVTGAENRGALPLHHLIEKLKEYHAAPALQGFGISSPEQVSAAVRAGAAGAISGSAIVKIIEKNLASPKQMLAELRSFVSAMKAASRA
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STRONG residues

12: N; 13: D; 14: R; 15: R; 16: E; 17: G; 18: A; 19: F; 20: V; 21: P; 22: F; 23: V; 24: T; 25: L; 26: G; 27: D; 28: P; 29: G; 30: I; 31: E; 32: Q; 33: S; 34: L; 35: K; 36: I; 37: I; 38: D; 39: T; 40: L; 41: I; 42: D; 43: A; 44: G; 45: A; 46: D; 47: A; 48: L; 49: E; 70: R; 71: A; 72: F; 73: A; 74: A; 75: G; 76: V; 77: T; 78: P; 79: A; 80: Q; 81: C; 82: F; 83: E; 84: M; 85: L; 86: A; 87: L; 88: I; 89: R; 90: E; 91: K; 92: H; 93: P; 94: T; 95: I; 96: P; 97: I; 98: G; 99: L; 100: L; 101: M; 115: Y; 116: A; 117: R; 118: C; 119: E; 120: Q; 121: V; 122: G; 123: V; 124: D;
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