Which Group Dynamics Matter: Social Predictors of Student Achievement in Team-Based Undergraduate Science Classrooms.

While group work in undergraduate science education tends to have overall benefit, less is known about the specific peer-peer dynamics that optimize learning during group interaction. The current study used peer ratings and self-reported data from 436 students enrolled in team-based undergraduate science courses (biology or chemistry) to determine group dynamics that predicted both willingness to work with peers in the future and individual achievement in the course. Results show that greater personal connection and contributions predicted willingness to work with a group member (R2biology = 0.75; R2chemistry = 0.59). While active contribution to a group predicted greater achievement, more noncontent interactions (e.g., encouragement, listening to feedback, being polite) predicted lower achievement, despite these being on-task and relevant. Additionally, having group members who were willing to continue working with a student was a positive predictor of that student's achievement regardless of course. Strikingly, students in chemistry were significantly less willing to work with women in their groups compared with men. Finally, not all forms of group conflict predict decreased achievement. These findings highlight group factors such as student behavior within the group, aspects of the group social environment, and peer support that can be targeted for optimizing undergraduate science learning.

Evaluation of α-hydroxycinnamic acids as pyruvate carboxylase inhibitors.

Through a structure-based drug design project (SBDD), potent small molecule inhibitors of pyruvate carboxylase (PC) have been discovered. A series of α-keto acids (7) and α-hydroxycinnamic acids (8) were prepared and evaluated for inhibition of PC in two assays. The two most potent inhibitors were 3,3'-(1,4-phenylene)bis[2-hydroxy-2-propenoic acid] (8u) and 2-hydroxy-3-(quinoline-2-yl)propenoic acid (8v) with IC50 values of 3.0 ±â€¯1.0 µM and 4.3 ±â€¯1.5 µM respectively. Compound 8v is a competitive inhibitor with respect to pyruvate (Ki = 0.74 µM) and a mixed-type inhibitor with respect to ATP, indicating that it targets the unique carboxyltransferase (CT) domain of PC. Furthermore, compound 8v does not significantly inhibit human carbonic anhydrase II, matrix metalloproteinase-2, malate dehydrogenase or lactate dehydrogenase.

A high-throughput screening assay for pyruvate carboxylase.

Pyruvate carboxylase (PC) catalyzes the conversion of pyruvate to oxaloacetate (OAA), an important metabolic reaction in a wide range of organisms. Small molecules directed against PC would enable detailed studies on the metabolic role of this enzyme and would have the potential to be developed into pharmacological agents. Currently, specific and potent small molecule regulators of PC are unavailable. To assist in efforts to find, develop, and characterize small molecule effectors of PC, a novel fixed-time assay has been developed based on the reaction of OAA with the diazonium salt, Fast Violet B (FVB), which produces a colored adduct with an absorbance maximum at 530 nm. This fixed time assay is reproducible, sensitive and responsive to known effectors of Rhizobium etli PC, Staphylococcus aureus PC, and Listeria monocytogenes PC, and is highly amenable to high-throughput screening. The assay was validated using a plate uniformity assessment test and a pilot screen of a library of 1280 compounds. The results indicate that the assay is suitable for screening small molecule libraries to find novel small molecule effectors of PC.

Inactivation of Mandelate Racemase by 3-Hydroxypyruvate Reveals a Potential Mechanistic Link between Enzyme Superfamilies.

Mandelate racemase (MR), a member of the enolase superfamily, catalyzes the Mg(2+)-dependent interconversion of the enantiomers of mandelate. Several α-keto acids are modest competitive inhibitors of MR [e.g., mesoxalate (Ki = 1.8 ± 0.3 mM) and 3-fluoropyruvate (Ki = 1.3 ± 0.1 mM)], but, surprisingly, 3-hydroxypyruvate (3-HP) is an irreversible, time-dependent inhibitor (kinact/KI = 83 ± 8 M(-1) s(-1)). Protection from inactivation by the competitive inhibitor benzohydroxamate, trypsinolysis and electrospray ionization tandem mass spectrometry analyses, and X-ray crystallographic studies reveal that 3-HP undergoes Schiff-base formation with Lys 166 at the active site, followed by formation of an aldehyde/enol(ate) adduct. Such a reaction is unprecedented in the enolase superfamily and may be a relic of an activity possessed by a promiscuous progenitor enzyme. The ability of MR to form and deprotonate a Schiff-base intermediate furnishes a previously unrecognized mechanistic link to other α/ß-barrel enzymes utilizing Schiff-base chemistry and is in accord with the sequence- and structure-based hypothesis that members of the metal-dependent enolase superfamily and the Schiff-base-forming N-acetylneuraminate lyase superfamily and aldolases share a common ancestor.