Background: Class I and II diterpene synthases, although poorly understood, generate diverse products. Results: Reported here is the structure of the bifunctional abietadiene synthase and supporting experimental/computational work. Conclusion: Visualization of the class I and II active sites confirms known and implicates new determinants of product formation. Significance: Residues, previously unrecognized, are assigned specific roles in substrate binding and catalysis.

Remarkable progress has recently been achieved in n-type and ambipolar OFETs. In this mini review, we will highlight the representative development of high performance n-type and ambipolar organic semiconductors (OSCs) especially for those n-type small OSCs with thin film mobilities >1 cm(2) V(-1) s(-1), and ambipolar small OSCs with both hole and electron mobilities of over 0.1 cm(2) V(-1) s(-1). This overview shall provide a meaningful guideline for further development of high performance n-type and ambipolar materials and devices.