TY - JOUR
T1 - Monkey electrophysiological and human psychophysical responses to mutants of the sweet protein brazzein
T2 - Delineating brazzein sweetness
AU - Jin, Zheyuan
AU - Danilova, Vicktoria
AU - Assadi-Porter, Fariba M.
AU - Markley, John L.
AU - Hellekant, Göran
PY - 2003/7
Y1 - 2003/7
N2 - Responses to brazzein 25 brazzein mutants and two forms of monellin were studied in two types of experiments: electrophysiological recordings from chorda tympani S fibers of the rhesus monkey, Macaca mulatta, and psychophysical experiments. We found that different mutations at position 29 (changing Asp29 to Ala, Lys or Asn) made the molecule significantly sweeter than brazzein, while mutations at positions 30 or 33 (Lys30Asp or Arg33Ala) removed all sweetness. The same pattern occurred again at the β-turn region, where Glu41 Lys gave the highest sweetness score among the mutants tested, whereas a mutation two residues distant (Arg43Ala) abolished the sweetness. The effects of charge and side chain size were examined at two locations, namely positions 29 and 36. The findings indicate that charge is important for eliciting sweetness, whereas the length of the side-chain plays a lesser role. We also found that the N- and C-termini are important for the sweetness of brazzein. The close correlation (r = 0.78) between the results of the above two methods corroborates our hypothesis that S fibers convey sweet taste in primates.
AB - Responses to brazzein 25 brazzein mutants and two forms of monellin were studied in two types of experiments: electrophysiological recordings from chorda tympani S fibers of the rhesus monkey, Macaca mulatta, and psychophysical experiments. We found that different mutations at position 29 (changing Asp29 to Ala, Lys or Asn) made the molecule significantly sweeter than brazzein, while mutations at positions 30 or 33 (Lys30Asp or Arg33Ala) removed all sweetness. The same pattern occurred again at the β-turn region, where Glu41 Lys gave the highest sweetness score among the mutants tested, whereas a mutation two residues distant (Arg43Ala) abolished the sweetness. The effects of charge and side chain size were examined at two locations, namely positions 29 and 36. The findings indicate that charge is important for eliciting sweetness, whereas the length of the side-chain plays a lesser role. We also found that the N- and C-termini are important for the sweetness of brazzein. The close correlation (r = 0.78) between the results of the above two methods corroborates our hypothesis that S fibers convey sweet taste in primates.
KW - Low-caloric natural sweeteners
KW - Magnitude labeled scale
KW - Rhesus monkey
KW - Sweet taste receptor
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U2 - 10.1093/chemse/28.6.491
DO - 10.1093/chemse/28.6.491
M3 - Article
C2 - 12907586
AN - SCOPUS:3042511803
SN - 0379-864X
VL - 28
SP - 491
EP - 498
JO - Chemical Senses
JF - Chemical Senses
IS - 6
ER -