Transaminase-Catalyzed Synthesis of β-Branched Noncanonical Amino Acids Driven by a Lysine Amine Donor.

Transaminases are choice biocatalysts for the synthesis of chiral primary amines, including amino acids bearing contiguous stereocenters. In this study, we employ lysine as a "smart" amine donor in transaminase-catalyzed dynamic kinetic resolution reactions to access β-branched noncanonical arylalanines. Our mechanistic investigation demonstrates that, upon transamination, the lysine-derived ketone byproduct readily cyclizes to a six-membered imine, driving the equilibrium in the desired direction and thus alleviating the need to load superstoichiometric quantities of the amine donor or deploy a multienzyme cascade.

Spatiotemporal walking gait kinematics of semi-arboreal red pandas (Ailurus fulgens).

Semi-arboreal mammals must routinely cope with the differing biomechanical challenges of terrestrial versus arboreal locomotion; however, it is not clear to what extent semi-arboreal mammals adjust footfall patterns when moving on different substrates. We opportunistically filmed quadrupedal locomotion (n = 132 walking strides) of semi-arboreal red pandas (Ailurus fulgens; n = 3) housed at Cleveland Metroparks Zoo and examined the effects of substrate type on spatiotemporal gait kinematic variables using linear mixed models. We further investigated the effects of substrate diameter and orientation on arboreal gait kinematics.

Jumping performance in tree squirrels: Insights into primate evolution.

Morphological traits suggesting powerful jumping abilities are characteristic of early crown primate fossils. Because tree squirrels lack certain 'primatelike' grasping features but frequently travel on the narrow terminal branches of trees, they make a viable extant model for an early stage of primate evolution. Here, we explore biomechanical determinants of jumping performance in the arboreal Eastern gray squirrel (Sciurus carolinensis, n = 3) as a greater understanding of the biomechanical strategies that squirrels use to modulate jumping performance could inform theories of selection for increased jumping ability during early primate evolution.

Aspects of molar form and dietary proclivities of African colobines.

This study investigates aspects of molar form in three African colobine species: Colobus polykomos, Colobus angolensis, and Piliocolobus badius. Our samples of C. polykomos and P.

Effects of honey locust seed pods on the behavior and nutrient intake of zoo-housed François langurs and prehensile-tailed porcupines.

Seed pods represent an under-utilized and valuable dietary resource for zoos because they encourage naturalistic extractive foraging behavior and because seeds pods, like leafy browses, are more fiber-rich than most dietary items typically offered in zoos. The primary goal of this study was to examine the effects of honey locust (Gleditsia triacanthos) seed pods on the behavior and macronutrient intake of zoo-housed François' langurs (Trachypithecus francoisi; n = 3) and prehensile-tailed porcupines (Coendou prehensilis; n = 2) using a pre- versus postdiet implementation design. From December 2019 to April 2020, we recorded behavior using instantaneous interval sampling and daily macronutrient intake via dietary intake records.

Balancing the scales: Preliminary investigation of total energy expenditure and daily metabolizable energy intake in Matschie's tree kangaroo (Dendrolagus matschiei).

Matschie's tree kangaroo (Dendrolagus matschiei) is an endangered arboreal marsupial native to Papua New Guinea. Detailed field studies of its behavior and ecology are scarce due largely to its occupation of remote cloud forests and cryptic nature. Although this species has been in human care since the 1950s, much of its biology is still unknown.

Asymmetric Alkylation of Ketones Catalyzed by Engineered TrpB.

The β-subunit of tryptophan synthase (TrpB) catalyzes a PLP-mediated β-substitution reaction between indole and serine to form L-Trp. A succession of TrpB protein engineering campaigns to expand the enzyme's nucleophile substrate range has enabled the biocatalytic production of diverse non-canonical amino acids (ncAAs). Here, we show that ketone-derived enolates can serve as nucleophiles in the TrpB reaction to achieve the asymmetric alkylation of ketones, an outstanding challenge in synthetic chemistry.

The Stabilizing Function of the Tail During Arboreal Quadrupedalism.

Locomotion on the narrow and compliant supports of the arboreal environment is inherently precarious. Previous studies have identified a host of morphological and behavioral specializations in arboreal animals broadly thought to promote stability when on precarious substrates. Less well-studied is the role of the tail in maintaining balance.

Quantifying Mineral Intake and the Role of Minerals on Food Selection in Angola Black and White Colobus Monkeys (Colobus angolensis palliatus).

Minerals are vital for many metabolic processes, and mineral deficiencies can adversely impact health and fitness. Mineral concentrations of food items are commonly reported in primate nutritional ecology studies and have been identified as important factors in primate food selection; however, very few studies have quantified daily mineral intake of free-ranging primates. We examined the concentration of 9 minerals (Ca, P, Mg, K, Na, Fe, Zn, Cu, and Mn) in foods consumed by Colobus angolensis palliatus inhabiting the Diani Forest of Kenya, and test whether individuals preferentially selected leaves in accordance with their mineral concentrations.

Nature's Machinery, Repurposed: Expanding the Repertoire of Iron-Dependent Oxygenases.

Iron is an especially important redox-active cofactor in biology because of its ability to mediate reactions with atmospheric O. Iron-dependent oxygenases exploit this earth-abundant transition metal for the insertion of oxygen atoms into organic compounds. Throughout the astounding diversity of transformations catalyzed by these enzymes, the protein framework directs reactive intermediates toward the precise formation of products, which, in many cases, necessitates the cleavage of strong C-H bonds.

Asymmetrical gait kinematics of free-ranging callitrichine primates in response to changes in substrate diameter and orientation.

Arboreal environments present considerable biomechanical challenges for animals moving and foraging among substrates varying in diameter, orientation and compliance. Most studies of quadrupedal gait kinematics in primates and other arboreal mammals have focused on symmetrical walking gaits and the significance of diagonal sequence gaits. Considerably less research has examined asymmetrical gaits, despite their prevalence in small-bodied arboreal taxa.

Effects of substrate and phylogeny on quadrupedal gait in free-ranging platyrrhines.

Objectives: Primate diagonal sequence (DS) gaits are often argued to be an adaptation for moving and foraging in the fine-branch niche; however, existing data have come predominantly from laboratory studies that are limited in taxonomic breadth and fail to account for the structural and ecological variation of natural substrates. We test the extent to which substrate diameter and orientation influence gait sequence type and limb phase in free-ranging primates, as well as how phylogenetic relatedness might condition response patterns.

Materials And Methods: We filmed quadrupedal locomotion in 11 platyrrhine species at field sites in Ecuador and Costa Rica and measured the diameter and orientation of locomotor substrates using remote sensors.

The effects of natural substrate discontinuities on the quadrupedal gait kinematics of free-ranging Saimiri sciureus.

Wild primates encounter complex matrices of substrates that differ in size, orientation, height, and compliance, and often move on multiple, discontinuous substrates within a single bout of locomotion. Our current understanding of primate gait is limited by artificial laboratory settings in which primate quadrupedal gait has primarily been studied. This study analyzes wild Saimiri sciureus (common squirrel monkey) gait on discontinuous substrates to capture the realistic effects of the complex arboreal habitat on walking kinematics.

My branch is your branch: Talar morphology correlates with relative substrate size in platyrrhines at Tiputini Biodiversity Station, Ecuador.

Given that most species of primates are predominantly arboreal, maintaining the ability to move among branches of varying sizes has presumably been a common selective force in primate evolution. However, empirical evaluations of the relationships between morphological variation and characteristics of substrate geometry, such as substrate diameter relative to an animal's body mass, have been limited by the lack of quantified substrate usage in the wild. Here we use recently published quantitative data to assess the relationships between relative substrate size and talar morphology in nine New World monkey species at the Tiputini Biodiversity Station, Ecuador.

Hydrogen Donation but not Abstraction by a Tyrosine (Y68) during Endoperoxide Installation by Verruculogen Synthase (FtmOx1).

Hydrogen-atom transfer (HAT) from a substrate carbon to an iron(IV)-oxo (ferryl) intermediate initiates a diverse array of enzymatic transformations. For outcomes other than hydroxylation, coupling of the resultant carbon radical and hydroxo ligand (oxygen rebound) must generally be averted. A recent study of FtmOx1, a fungal iron(II)- and 2-(oxo)glutarate-dependent oxygenase that installs the endoperoxide of verruculogen by adding O between carbons 21 and 27 of fumitremorgin B, posited that tyrosine (Tyr or Y) 224 serves as HAT intermediary to separate the C21 radical (C21•) and Fe(III)-OH HAT products and prevent rebound.

α-Amine Desaturation of d-Arginine by the Iron(II)- and 2-(Oxo)glutarate-Dependent l-Arginine 3-Hydroxylase, VioC.

When challenged with substrate analogues, iron(II)- and 2-(oxo)glutarate-dependent (Fe/2OG) oxygenases can promote transformations different from those they enact upon their native substrates. We show here that the Fe/2OG enzyme, VioC, which is natively an l-arginine 3-hydroxylase, catalyzes an efficient oxidative deamination of its substrate enantiomer, d-Arg. The reactant complex with d-Arg retains all interactions between enzyme and substrate functional groups, but the required structural adjustments and opposite configuration of C2 position this carbon more optimally than C3 to donate hydrogen (H) to the ferryl intermediate.

Locomotor kinematics of tree squirrels (Sciurus carolinensis) in free-ranging and laboratory environments: Implications for primate locomotion and evolution.

The grasping capabilities and gait kinematics characteristic of primates are often argued to be adaptations for safely moving on small terminal branches. The goal of this study was to identify whether Eastern gray squirrels (Sciurus carolinensis)-arboreal rodents that frequently move and forage on small branches, lack primate-like grasping and gait patterns, and arguably represent extant analogs of a stem primate ancestor-adjust gait kinematics to narrow and nonhorizontal branches. We studied locomotor kinematics of free-ranging and laboratory-housed squirrels moving over various substrates.

A user's guide for the quantitative analysis of substrate characteristics and locomotor kinematics in free-ranging primates.

Objectives: Laboratory studies have yielded important insights into primate locomotor mechanics. Nevertheless, laboratory studies fail to capture the range of ecological and structural variation encountered by free-ranging primates. We present techniques for collecting kinematic data on wild primates using consumer grade high-speed cameras and demonstrate novel methods for quantifying metric variation in arboreal substrates.

Nutrient intake and balancing among female Colobus angolensis palliatus inhabiting structurally distinct forest areas: Effects of group, season, and reproductive state.

Understanding intraspecific behavioral and dietary variation is critical for assessing primate populations' abilities to persist in habitats characterized by increasing anthropogenic disturbances. While it is evident that some species exhibit considerable dietary flexibility (in terms of species-specific plant parts) in relation to habitat disturbance, it is unclear if primates are characterized by similar variation and flexibility regarding nutrient intake. This study examined the effects of group, season, and reproductive state on nutrient intake and balancing in adult female Colobus angolensis palliatus in the Diani Forest, Kenya.

Two Distinct Mechanisms for C-C Desaturation by Iron(II)- and 2-(Oxo)glutarate-Dependent Oxygenases: Importance of α-Heteroatom Assistance.

Hydroxylation of aliphatic carbons by nonheme Fe(IV)-oxo (ferryl) complexes proceeds by hydrogen-atom (H•) transfer (HAT) to the ferryl and subsequent coupling between the carbon radical and Fe(III)-coordinated oxygen (termed rebound). Enzymes that use H•-abstracting ferryl complexes for other transformations must either suppress rebound or further process hydroxylated intermediates. For olefin-installing C-C desaturations, it has been proposed that a second HAT to the Fe(III)-OH complex from the carbon α to the radical preempts rebound.

Visualizing the Reaction Cycle in an Iron(II)- and 2-(Oxo)-glutarate-Dependent Hydroxylase.

Iron(II)- and 2-(oxo)-glutarate-dependent oxygenases catalyze diverse oxidative transformations that are often initiated by abstraction of hydrogen from carbon by iron(IV)-oxo (ferryl) complexes. Control of the relative orientation of the substrate C-H and ferryl Fe-O bonds, primarily by direction of the oxo group into one of two cis-related coordination sites (termed inline and offline), may be generally important for control of the reaction outcome. Neither the ferryl complexes nor their fleeting precursors have been crystallographically characterized, hindering direct experimental validation of the offline hypothesis and elucidation of the means by which the protein might dictate an alternative oxo position.

AgHalo: A Facile Fluorogenic Sensor to Detect Drug-Induced Proteome Stress.

Drug-induced proteome stress that involves protein aggregation may cause adverse effects and undermine the safety profile of a drug. Safety of drugs is regularly evaluated using cytotoxicity assays that measure cell death. However, these assays provide limited insights into the presence of proteome stress in live cells.

The Cation-π Interaction Enables a Halo-Tag Fluorogenic Probe for Fast No-Wash Live Cell Imaging and Gel-Free Protein Quantification.

The design of fluorogenic probes for a Halo tag is highly desirable but challenging. Previous work achieved this goal by controlling the chemical switch of spirolactones upon the covalent conjugation between the Halo tag and probes or by incorporating a "channel dye" into the substrate binding tunnel of the Halo tag. In this work, we have developed a novel class of Halo-tag fluorogenic probes that are derived from solvatochromic fluorophores.