{"product_id":"kinessa-8-nm-per-step-physics-t-shirt","title":"Kinessa – 8 nm per Step Physics T-Shirt","description":"\u003cp\u003eKinessa walks a microtubule tightrope with a cargo sphere on her back, one ATP per stride, hand over hand.\u003c\/p\u003e\u003ch3\u003eThe Physics\u003c\/h3\u003e\u003cp\u003eKinesin-1 is a two-headed motor protein that carries cargo along microtubules. Using an optical trap, Svoboda, Schmidt, Schnapp and Block saw discrete 8 nm steps of the molecule's centre of mass. Yildiz and colleagues labelled one head and saw it move in alternating steps of about 17 nm and 0 nm: the heads swap places, hand over hand.\u003c\/p\u003e\u003cp\u003eWith a force clamp, Visscher, Schnitzer and Block (1999) found one ATP hydrolysed per 8 nm step and a stall force that depends on ATP concentration. Summarising those measurements, Schnitzer, Visscher and Block (2000) put the motor's maximum load at about 5.5–7.5 pN.\u003c\/p\u003e\u003cp\u003e\u003cstrong\u003eW = F × d = 6 pN × 8 nm = 48 pN·nm ≈ 12 k_BT\u003c\/strong\u003e\u003c\/p\u003e\u003cul\u003e\n\u003cli\u003eW: work per step (pN·nm)\u003c\/li\u003e\n\u003cli\u003eF: load force, near stall (pN)\u003c\/li\u003e\n\u003cli\u003ed: step size (nm)\u003c\/li\u003e\n\u003cli\u003ek_BT: thermal energy, 4.1 pN·nm at 298 K\u003c\/li\u003e\n\u003c\/ul\u003e\u003cp\u003eSvoboda et al., Nature 365, 721 (1993); Visscher et al., Nature 400, 184 (1999); Schnitzer et al., Nat. Cell Biol. 2, 718 (2000); Yildiz et al., Science 303, 676 (2004).\u003c\/p\u003e\u003cp\u003e\u003cem\u003eHonest caveat:\u003c\/em\u003e The stall force is not always 6 pN; it depends on conditions. 48\/4.1 is 11.7, so “about 12 k_BT”.\u003c\/p\u003e\u003ch3\u003eOn the shirt\u003c\/h3\u003e\u003cp\u003eFront: Kinessa, the pixel-art character, with “8 NM PER STEP”. Back: the one-ATP step, the stall force, the work per step in k_BT and the 1993, 1999 and 2004 sources. Printed on a unisex tee.\u003c\/p\u003e","brand":"Printify","offers":[{"title":"S \/ White","offer_id":50960510419047,"sku":"11117567960688139574","price":29.99,"currency_code":"USD","in_stock":true},{"title":"S \/ Black","offer_id":50960510451815,"sku":"26890489265442360678","price":29.99,"currency_code":"USD","in_stock":true},{"title":"M \/ White","offer_id":50960510484583,"sku":"20655217327623028452","price":29.99,"currency_code":"USD","in_stock":true},{"title":"M \/ Black","offer_id":50960510517351,"sku":"23796624530195152702","price":29.99,"currency_code":"USD","in_stock":true},{"title":"L \/ White","offer_id":50960510550119,"sku":"85385869063688252158","price":29.99,"currency_code":"USD","in_stock":true},{"title":"L \/ Black","offer_id":50960510582887,"sku":"19755560731096002838","price":29.99,"currency_code":"USD","in_stock":true},{"title":"XL \/ White","offer_id":50960510615655,"sku":"16828516723921951728","price":29.99,"currency_code":"USD","in_stock":true},{"title":"XL \/ Black","offer_id":50960510648423,"sku":"17778967294796756324","price":29.99,"currency_code":"USD","in_stock":true},{"title":"2XL \/ White","offer_id":50960510681191,"sku":"45989124123271880654","price":29.99,"currency_code":"USD","in_stock":true},{"title":"2XL \/ Black","offer_id":50960510713959,"sku":"13474565052253083673","price":29.99,"currency_code":"USD","in_stock":true},{"title":"3XL \/ White","offer_id":50960510746727,"sku":"16953539059067610080","price":29.99,"currency_code":"USD","in_stock":true},{"title":"3XL \/ Black","offer_id":50960510779495,"sku":"75446288505319059695","price":29.99,"currency_code":"USD","in_stock":true},{"title":"4XL \/ White","offer_id":50960510812263,"sku":"31297456471150907852","price":29.99,"currency_code":"USD","in_stock":true},{"title":"4XL \/ Black","offer_id":50960510845031,"sku":"25366065837790803334","price":29.99,"currency_code":"USD","in_stock":true},{"title":"5XL \/ White","offer_id":50960510877799,"sku":"26205846310701163484","price":29.99,"currency_code":"USD","in_stock":true},{"title":"5XL \/ Black","offer_id":50960510910567,"sku":"64061806647830810887","price":29.99,"currency_code":"USD","in_stock":true}],"thumbnail_url":"\/\/cdn.shopify.com\/s\/files\/1\/0596\/8746\/9159\/files\/kinesin-step_front_16_white.png?v=1793625626","url":"https:\/\/pixelatedphysics.com\/products\/kinessa-8-nm-per-step-physics-t-shirt","provider":"Pixelated Physics","version":"1.0","type":"link"}